Enable TypeScript strict:true, and more typescript-eslint rules (#1223)

* Catch promise errors better * Move subFunctions to bottom of createNewWindow * Use parents when creating child BrowserWindow instances * Some about:blank pages have an anchor (for some reason) * Inject browserWindowOptions better * Interim refactor to MainWindow object * Split up the window functions/helpers/events some * Further separate out window functions + tests * Add a mock for unit testing functions that access electron * Add unit tests for onWillPreventUnload * Improve windowEvents tests * Add the first test for windowHelpers * Move WebRequest event handling to node * insertCSS completely under test * clearAppData completely under test * Fix contextMenu require bug * More tests + fixes * Fix + add to createNewTab tests * Convert createMainWindow back to func + work out gremlins * Move setupWindow away from main since its shared * Make sure contextMenu is handling promises * Fix issues with fullscreen not working + menu refactor * Run jest against app/dist so that we can hit app unit tests as well * Requested PR changes * Add strict typing; tests currently failing * Fix failing unit tests * Add some more eslint warnings and fixes * More eslint fixes * Strict typing on (still issues with the lib dir) * Fix the package.json import/require * Fix some funky test errors * Warn -> Error for eslint rules * @ts-ignore -> @ts-expect-error * Add back the ext code I removed
2021-06-15 22:20:49 -04:00 · 2021-06-15 22:20:49 -04:00 · 7a08a2d676
parent 7807bbb327
commit 7a08a2d676
47 changed files with 919 additions and 540 deletions
--- a/.eslintrc.js
+++ b/.eslintrc.js
@ -17,25 +17,29 @@ module.exports = {
  rules: {
    'no-console': 'error',
    'prettier/prettier': [
-      'error', {
-        'endOfLine': 'auto'
-      }
+      'error',
+      {
+        endOfLine: 'auto',
+      },
    ],
-    // TODO remove when done killing `any`s and making tsc strict
-    '@typescript-eslint/ban-ts-comment': 'off',
-    '@typescript-eslint/no-explicit-any': 'off',
-    '@typescript-eslint/no-unsafe-assignment': 'off',
-    '@typescript-eslint/no-unsafe-call': 'off',
-    '@typescript-eslint/no-unsafe-member-access': 'off',
-    '@typescript-eslint/no-unsafe-return': 'off',
+    '@typescript-eslint/explicit-function-return-type': 'error',
+    '@typescript-eslint/no-confusing-non-null-assertion': 'error',
+    '@typescript-eslint/no-explicit-any': 'error',
+    '@typescript-eslint/no-extraneous-class': 'error',
+    '@typescript-eslint/no-implicit-any-catch': 'error',
+    '@typescript-eslint/no-invalid-void-type': 'error',
+    '@typescript-eslint/prefer-ts-expect-error': 'error',
+    '@typescript-eslint/type-annotation-spacing': 'error',
+    '@typescript-eslint/typedef': 'error',
+    '@typescript-eslint/unified-signatures': 'error',
  },
  // https://eslint.org/docs/user-guide/configuring/ignoring-code#ignorepatterns-in-config-files
  ignorePatterns: [
-    "node_modules/**",
-    "app/node_modules/**",
-    "app/lib/**",
-    "lib/**",
-    "built-tests/**",
-    "coverage/**",
-  ]
+    'node_modules/**',
+    'app/node_modules/**',
+    'app/lib/**',
+    'lib/**',
+    'built-tests/**',
+    'coverage/**',
+  ],
 };
--- a/.gitignore
+++ b/.gitignore
@ -60,3 +60,5 @@ nativefier*.tgz

 # https://github.com/nektos/act
 .actrc
+
+tsconfig.tsbuildinfo
--- a/app/src/components/mainWindow.ts
+++ b/app/src/components/mainWindow.ts
@ -25,14 +25,14 @@ export const APP_ARGS_FILE_PATH = path.join(__dirname, '..', 'nativefier.json');
 type SessionInteractionRequest = {
  id?: string;
  func?: string;
-  funcArgs?: any[];
+  funcArgs?: unknown[];
  property?: string;
-  propertyValue?: any;
+  propertyValue?: unknown;
 };

 type SessionInteractionResult = {
  id?: string;
-  value?: any;
+  value?: unknown;
  error?: Error;
 };

@ -144,20 +144,17 @@ function createContextMenu(options, window: BrowserWindow): void {
  }
 }

-export function saveAppArgs(newAppArgs: any) {
+export function saveAppArgs(newAppArgs: any): void {
  try {
    fs.writeFileSync(APP_ARGS_FILE_PATH, JSON.stringify(newAppArgs));
-  } catch (err) {
-    // eslint-disable-next-line no-console
+  } catch (err: unknown) {
    log.warn(
-      `WARNING: Ignored nativefier.json rewrital (${(
-        err as Error
-      ).toString()})`,
+      `WARNING: Ignored nativefier.json rewrital (${(err as Error).message})`,
    );
  }
 }

-function setupCloseEvent(options, window: BrowserWindow) {
+function setupCloseEvent(options, window: BrowserWindow): void {
  window.on('close', (event: IpcMainEvent) => {
    log.debug('mainWindow.close', event);
    if (window.isFullScreen()) {
@ -181,7 +178,7 @@ function setupCounter(
  options,
  window: BrowserWindow,
  setDockBadge: (value: number | string, bounce?: boolean) => void,
-) {
+): void {
  window.on('page-title-updated', (event, title) => {
    log.debug('mainWindow.page-title-updated', { event, title });
    const counterValue = getCounterValue(title);
@ -242,7 +239,7 @@ function setupSessionInteraction(options, window: BrowserWindow): void {
            typeof result.value['then'] === 'function'
          ) {
            // This is a promise. We'll resolve it here otherwise it will blow up trying to serialize it in the reply
-            result.value
+            (result.value as Promise<unknown>)
              .then((trueResultValue) => {
                result.value = trueResultValue;
                log.debug('ipcMain.session-interaction:result', result);
@ -274,9 +271,9 @@ function setupSessionInteraction(options, window: BrowserWindow): void {
          log.debug('session-interaction:result', result);
          event.reply('session-interaction-reply', result);
        }
-      } catch (error) {
-        log.error('session-interaction:error', error, event, request);
-        result.error = error;
+      } catch (err: unknown) {
+        log.error('session-interaction:error', err, event, request);
+        result.error = err as Error;
        result.value = undefined; // Clear out the value in case serializing the value is what got us into this mess in the first place
        event.reply('session-interaction-reply', result);
      }
--- a/app/src/components/menu.ts
+++ b/app/src/components/menu.ts
@ -89,9 +89,7 @@ export function generateMenu(
      {
        label: 'Copy Current URL',
        accelerator: 'CmdOrCtrl+L',
-        click: () => {
-          clipboard.writeText(getCurrentURL());
-        },
+        click: (): void => clipboard.writeText(getCurrentURL()),
      },
      {
        label: 'Paste',
@ -110,7 +108,7 @@ export function generateMenu(
      },
      {
        label: 'Clear App Data',
-        click: (item: MenuItem, focusedWindow: BrowserWindow) => {
+        click: (item: MenuItem, focusedWindow: BrowserWindow): void => {
          log.debug('Clear App Data.click', {
            item,
            focusedWindow,
@ -166,7 +164,7 @@ export function generateMenu(
        accelerator: isOSX() ? 'Ctrl+Cmd+F' : 'F11',
        enabled: mainWindow.isFullScreenable() || isOSX(),
        visible: mainWindow.isFullScreenable() || isOSX(),
-        click: (item: MenuItem, focusedWindow: BrowserWindow) => {
+        click: (item: MenuItem, focusedWindow: BrowserWindow): void => {
          log.debug('Toggle Full Screen.click()', {
            item,
            focusedWindow,
@ -266,9 +264,9 @@ export function generateMenu(
    submenu: [
      {
        label: `Built with Nativefier v${nativefierVersion}`,
-        click: () => {
+        click: (): void => {
          openExternal('https://github.com/nativefier/nativefier').catch(
-            (err) =>
+            (err: unknown): void =>
              log.error(
                'Built with Nativefier v${nativefierVersion}.click ERROR',
                err,
@ -278,9 +276,10 @@ export function generateMenu(
      },
      {
        label: 'Report an Issue',
-        click: () => {
+        click: (): void => {
          openExternal('https://github.com/nativefier/nativefier/issues').catch(
-            (err) => log.error('Report an Issue.click ERROR', err),
+            (err: unknown): void =>
+              log.error('Report an Issue.click ERROR', err),
          );
        },
      },
@ -370,8 +369,8 @@ function injectBookmarks(menuTemplate: MenuItemConstructorOptions[]): void {
            }
            return {
              label: bookmark.title,
-              click: () => {
-                goToURL(bookmark.url).catch((err) =>
+              click: (): void => {
+                goToURL(bookmark.url).catch((err: unknown): void =>
                  log.error(`${bookmark.title}.click ERROR`, err),
                );
              },
@ -390,7 +389,7 @@ function injectBookmarks(menuTemplate: MenuItemConstructorOptions[]): void {
    };
    // Insert custom bookmarks menu between menus "View" and "Window"
    menuTemplate.splice(menuTemplate.length - 2, 0, bookmarksMenu);
-  } catch (err) {
+  } catch (err: unknown) {
    log.error('Failed to load & parse bookmarks configuration JSON file.', err);
  }
 }
--- a/app/src/components/trayIcon.ts
+++ b/app/src/components/trayIcon.ts
@ -23,7 +23,7 @@ export function createTrayIcon(
      appIcon.setImage(nimage);
    }

-    const onClick = () => {
+    const onClick = (): void => {
      log.debug('onClick');
      if (mainWindow.isVisible()) {
        mainWindow.hide();
--- a/app/src/helpers/helpers.ts
+++ b/app/src/helpers/helpers.ts
@ -141,7 +141,7 @@ export function linkIsInternal(
    // Only use the tld and the main domain for domain-ish test
    // Enables domain-ish equality for blog.foo.com and shop.foo.com
    return domainify(currentUrl) === domainify(newUrl);
-  } catch (err) {
+  } catch (err: unknown) {
    log.error(
      'Failed to parse domains as determining if link is internal. From:',
      currentUrl,
--- a/app/src/helpers/inferFlash.ts
+++ b/app/src/helpers/inferFlash.ts
@ -4,6 +4,8 @@ import * as path from 'path';

 import { isOSX, isWindows, isLinux } from './helpers';

+type fsError = Error & { code: string };
+
 /**
 * Find a file or directory
 */
@ -14,12 +16,12 @@ function findSync(
 ): string[] {
  const matches: string[] = [];

-  (function findSyncRecurse(base) {
+  (function findSyncRecurse(base): void {
    let children: string[];
    try {
      children = fs.readdirSync(base);
-    } catch (err) {
-      if (err.code === 'ENOENT') {
+    } catch (err: unknown) {
+      if ((err as fsError).code === 'ENOENT') {
        return;
      }
      throw err;
@ -51,18 +53,18 @@ function findSync(
  return matches;
 }

-function findFlashOnLinux() {
+function findFlashOnLinux(): string {
  return findSync(/libpepflashplayer\.so/, '/opt/google/chrome')[0];
 }

-function findFlashOnWindows() {
+function findFlashOnWindows(): string {
  return findSync(
    /pepflashplayer\.dll/,
    'C:\\Program Files (x86)\\Google\\Chrome',
  )[0];
 }

-function findFlashOnMac() {
+function findFlashOnMac(): string {
  return findSync(
    /PepperFlashPlayer.plugin/,
    '/Applications/Google Chrome.app/',
@ -70,7 +72,7 @@ function findFlashOnMac() {
  )[0];
 }

-export function inferFlashPath() {
+export function inferFlashPath(): string {
  if (isOSX()) {
    return findFlashOnMac();
  }
--- a/app/src/helpers/windowEvents.ts
+++ b/app/src/helpers/windowEvents.ts
@ -1,4 +1,10 @@
-import { dialog, BrowserWindow, IpcMainEvent, WebContents } from 'electron';
+import {
+  dialog,
+  BrowserWindow,
+  IpcMainEvent,
+  NewWindowWebContentsEvent,
+  WebContents,
+} from 'electron';
 import log from 'loglevel';

 import { linkIsInternal, nativeTabsSupported, openExternal } from './helpers';
@ -14,7 +20,7 @@ import {
 export function onNewWindow(
  options,
  setupWindow: (...args) => void,
-  event: Event & { newGuest?: any },
+  event: NewWindowWebContentsEvent,
  urlToGo: string,
  frameName: string,
  disposition:
@ -33,7 +39,7 @@ export function onNewWindow(
    disposition,
    parent,
  });
-  const preventDefault = (newGuest: any): void => {
+  const preventDefault = (newGuest: BrowserWindow): void => {
    event.preventDefault();
    if (newGuest) {
      event.newGuest = newGuest;
@ -96,7 +102,7 @@ export function onNewWindowHelper(
      }
    }
    return Promise.resolve(undefined);
-  } catch (err) {
+  } catch (err: unknown) {
    return Promise.reject(err);
  }
 }
@ -153,7 +159,7 @@ export function setupNativefierWindow(options, window: BrowserWindow): void {

  window.webContents.on('will-navigate', (event: IpcMainEvent, url: string) => {
    onWillNavigate(options, event, url).catch((err) => {
-      log.error(' window.webContents.on.will-navigate ERROR', err);
+      log.error('window.webContents.on.will-navigate ERROR', err);
      event.preventDefault();
    });
  });
@ -161,14 +167,14 @@ export function setupNativefierWindow(options, window: BrowserWindow): void {

  sendParamsOnDidFinishLoad(options, window);

-  // @ts-ignore new-tab isn't in the type definition, but it does exist
-  window.on('new-tab', () => {
+  // @ts-expect-error new-tab isn't in the type definition, but it does exist
+  window.on('new-tab', () =>
    createNewTab(
      options,
      setupNativefierWindow,
      options.targetUrl,
      true,
      window,
-    ).catch((err) => log.error('new-tab ERROR', err));
-  });
+    ),
+  );
 }
--- a/app/src/helpers/windowHelpers.test.ts
+++ b/app/src/helpers/windowHelpers.test.ts
@ -140,7 +140,7 @@ describe('injectCSS', () => {
    expect(mockGetCSSToInject).toHaveBeenCalled();

    window.webContents.emit('did-navigate');
-    // @ts-ignore this function doesn't exist in the actual electron version, but will in our mock
+    // @ts-expect-error this function doesn't exist in the actual electron version, but will in our mock
    window.webContents.session.webRequest.send(
      'onHeadersReceived',
      { responseHeaders, webContents: window.webContents },
@ -167,7 +167,7 @@ describe('injectCSS', () => {
    expect(mockGetCSSToInject).toHaveBeenCalled();

    window.webContents.emit('did-navigate');
-    // @ts-ignore this function doesn't exist in the actual electron version, but will in our mock
+    // @ts-expect-error this function doesn't exist in the actual electron version, but will in our mock
    window.webContents.session.webRequest.send(
      'onHeadersReceived',
      { responseHeaders, webContents: window.webContents },
@ -202,7 +202,7 @@ describe('injectCSS', () => {

      expect(window.webContents.emit('did-navigate')).toBe(true);
      mockWebContentsInsertCSS.mockReset().mockResolvedValue(undefined);
-      // @ts-ignore this function doesn't exist in the actual electron version, but will in our mock
+      // @ts-expect-error this function doesn't exist in the actual electron version, but will in our mock
      window.webContents.session.webRequest.send(
        'onHeadersReceived',
        {
@ -235,7 +235,7 @@ describe('injectCSS', () => {

      window.webContents.emit('did-navigate');
      mockWebContentsInsertCSS.mockReset().mockResolvedValue(undefined);
-      // @ts-ignore this function doesn't exist in the actual electron version, but will in our mock
+      // @ts-expect-error this function doesn't exist in the actual electron version, but will in our mock
      window.webContents.session.webRequest.send(
        'onHeadersReceived',
        {
@ -270,7 +270,7 @@ describe('injectCSS', () => {

      window.webContents.emit('did-navigate');
      mockWebContentsInsertCSS.mockReset().mockResolvedValue(undefined);
-      // @ts-ignore this function doesn't exist in the actual electron version, but will in our mock
+      // @ts-expect-error this function doesn't exist in the actual electron version, but will in our mock
      window.webContents.session.webRequest.send(
        'onHeadersReceived',
        {
@ -302,7 +302,7 @@ describe('injectCSS', () => {

      window.webContents.emit('did-navigate');
      mockWebContentsInsertCSS.mockReset().mockResolvedValue(undefined);
-      // @ts-ignore this function doesn't exist in the actual electron version, but will in our mock
+      // @ts-expect-error this function doesn't exist in the actual electron version, but will in our mock
      window.webContents.session.webRequest.send(
        'onHeadersReceived',
        {
--- a/app/src/helpers/windowHelpers.ts
+++ b/app/src/helpers/windowHelpers.ts
@ -83,7 +83,7 @@ export function createNewTab(
  url: string,
  foreground: boolean,
  parent?: BrowserWindow,
-): Promise<BrowserWindow> {
+): BrowserWindow {
  log.debug('createNewTab', { url, foreground, parent });
  return withFocusedWindow((focusedWindow) => {
    const newTab = createNewWindow(options, setupWindow, url, parent);
@ -314,7 +314,7 @@ export function setProxyRules(window: BrowserWindow, proxyRules): void {
    .catch((err) => log.error('session.setProxy ERROR', err));
 }

-export function withFocusedWindow(block: (window: BrowserWindow) => any): any {
+export function withFocusedWindow<T>(block: (window: BrowserWindow) => T): T {
  const focusedWindow = BrowserWindow.getFocusedWindow();
  if (focusedWindow) {
    return block(focusedWindow);
--- a/app/src/main.ts
+++ b/app/src/main.ts
@ -3,7 +3,7 @@ import 'source-map-support/register';
 import fs from 'fs';
 import * as path from 'path';

-import {
+import electron, {
  app,
  crashReporter,
  dialog,
@ -67,10 +67,11 @@ if (process.argv.length > 1) {
    new URL(maybeUrl);
    appArgs.targetUrl = maybeUrl;
    log.info('Loading override URL passed as argument:', maybeUrl);
-  } catch (err) {
+  } catch (err: unknown) {
    log.error(
      'Not loading override URL passed as argument, because failed to parse:',
      maybeUrl,
+      err,
    );
  }
 }
@ -155,12 +156,12 @@ if (appArgs.lang) {

 let currentBadgeCount = 0;
 const setDockBadge = isOSX()
-  ? (count: number, bounce = false) => {
+  ? (count: number, bounce = false): void => {
      app.dock.setBadge(count.toString());
      if (bounce && count > currentBadgeCount) app.dock.bounce();
      currentBadgeCount = count;
    }
-  : () => undefined;
+  : (): void => undefined;

 app.on('window-all-closed', () => {
  log.debug('app.window-all-closed');
@ -203,14 +204,14 @@ if (appArgs.crashReporter) {
 }

 if (appArgs.widevine) {
-  // @ts-ignore This event only appears on the widevine version of electron, which we'd see at runtime
+  // @ts-expect-error This event only appears on the widevine version of electron, which we'd see at runtime
  app.on('widevine-ready', (version: string, lastVersion: string) => {
    log.debug('app.widevine-ready', { version, lastVersion });
    onReady().catch((err) => log.error('onReady ERROR', err));
  });

  app.on(
-    // @ts-ignore This event only appears on the widevine version of electron, which we'd see at runtime
+    // @ts-expect-error This event only appears on the widevine version of electron, which we'd see at runtime
    'widevine-update-pending',
    (currentVersion: string, pendingVersion: string) => {
      log.debug('app.widevine-update-pending', {
@ -220,8 +221,8 @@ if (appArgs.widevine) {
    },
  );

-  // @ts-ignore This event only appears on the widevine version of electron, which we'd see at runtime
-  app.on('widevine-error', (error: any) => {
+  // @ts-expect-error This event only appears on the widevine version of electron, which we'd see at runtime
+  app.on('widevine-error', (error: Error) => {
    log.error('app.widevine-error', error);
  });
 } else {
@ -231,7 +232,7 @@ if (appArgs.widevine) {
  });
 }

-app.on('activate', (event, hasVisibleWindows) => {
+app.on('activate', (event: electron.Event, hasVisibleWindows: boolean) => {
  log.debug('app.activate', { event, hasVisibleWindows });
  if (isOSX()) {
    // this is called when the dock is clicked
@ -374,7 +375,7 @@ app.on(

 app.on(
  'activity-was-continued',
-  (event: IpcMainEvent, type: string, userInfo: any) => {
+  (event: IpcMainEvent, type: string, userInfo: unknown) => {
    log.debug('app.activity-was-continued', { event, type, userInfo });
  },
 );
--- a/app/src/mocks/electron.ts
+++ b/app/src/mocks/electron.ts
@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/no-extraneous-class */
 /* eslint-disable @typescript-eslint/no-unused-vars */
 import { EventEmitter } from 'events';

@ -21,12 +22,12 @@ import { EventEmitter } from 'events';
 class MockBrowserWindow extends EventEmitter {
  webContents: MockWebContents;

-  constructor(options?: any) {
+  constructor(options?: unknown) {
    super(options);
    this.webContents = new MockWebContents();
  }

-  addTabbedWindow(tab: MockBrowserWindow) {
+  addTabbedWindow(tab: MockBrowserWindow): void {
    return;
  }

@ -54,7 +55,7 @@ class MockBrowserWindow extends EventEmitter {
    return undefined;
  }

-  loadURL(url: string, options?: any): Promise<void> {
+  loadURL(url: string, options?: unknown): Promise<void> {
    return Promise.resolve(undefined);
  }

@ -70,14 +71,14 @@ class MockBrowserWindow extends EventEmitter {
 class MockDialog {
  static showMessageBox(
    browserWindow: MockBrowserWindow,
-    options: any,
+    options: unknown,
  ): Promise<number> {
    return Promise.resolve(undefined);
  }

  static showMessageBoxSync(
    browserWindow: MockBrowserWindow,
-    options: any,
+    options: unknown,
  ): number {
    return undefined;
  }
@ -112,7 +113,7 @@ class MockWebContents extends EventEmitter {
    return undefined;
  }

-  insertCSS(css: string, options?: any): Promise<string> {
+  insertCSS(css: string, options?: unknown): Promise<string> {
    return Promise.resolve(undefined);
  }
 }
@ -125,22 +126,24 @@ class MockWebRequest {
  }

  onHeadersReceived(
-    filter: any,
+    filter: unknown,
    listener:
      | ((
-          details: any,
-          callback: (headersReceivedResponse: any) => void,
+          details: unknown,
+          callback: (headersReceivedResponse: unknown) => void,
        ) => void)
      | null,
  ): void {
    this.emitter.addListener(
      'onHeadersReceived',
-      (details: any, callback: (headersReceivedResponse: any) => void) =>
-        listener(details, callback),
+      (
+        details: unknown,
+        callback: (headersReceivedResponse: unknown) => void,
+      ) => listener(details, callback),
    );
  }

-  send(event: string, ...args: any[]): void {
+  send(event: string, ...args: unknown[]): void {
    this.emitter.emit(event, ...args);
  }
 }
--- a/app/src/preload.ts
+++ b/app/src/preload.ts
@ -34,9 +34,18 @@ export const INJECT_DIR = path.join(__dirname, '..', 'inject');
 * @param createCallback
 * @param clickCallback
 */
-function setNotificationCallback(createCallback, clickCallback) {
+function setNotificationCallback(
+  createCallback: {
+    (title: string, opt: NotificationOptions): void;
+    (...args: unknown[]): void;
+  },
+  clickCallback: { (): void; (this: Notification, ev: Event): unknown },
+): void {
  const OldNotify = window.Notification;
-  const newNotify = function (title, opt) {
+  const newNotify = function (
+    title: string,
+    opt: NotificationOptions,
+  ): Notification {
    createCallback(title, opt);
    const instance = new OldNotify(title, opt);
    instance.addEventListener('click', clickCallback);
@ -47,11 +56,11 @@ function setNotificationCallback(createCallback, clickCallback) {
    get: () => OldNotify.permission,
  });

-  // @ts-ignore
+  // @ts-expect-error
  window.Notification = newNotify;
 }

-function injectScripts() {
+function injectScripts(): void {
  const needToInject = fs.existsSync(INJECT_DIR);
  if (!needToInject) {
    return;
@ -68,15 +77,18 @@ function injectScripts() {
      log.debug('Injecting JS file', jsFile);
      require(jsFile);
    }
-  } catch (error) {
-    log.error('Error encoutered injecting JS files', error);
+  } catch (err: unknown) {
+    log.error('Error encoutered injecting JS files', err);
  }
 }

-function notifyNotificationCreate(title, opt) {
+function notifyNotificationCreate(
+  title: string,
+  opt: NotificationOptions,
+): void {
  ipcRenderer.send('notification', title, opt);
 }
-function notifyNotificationClick() {
+function notifyNotificationClick(): void {
  ipcRenderer.send('notification-click');
 }

--- a/package.json
+++ b/package.json
@ -37,8 +37,8 @@
    "build:watch": "npm run clean && tsc --build . app --watch",
    "changelog": "./.github/generate-changelog",
    "ci": "npm run lint && npm test",
-    "clean": "rimraf lib/ app/lib/ app/dist/",
-    "clean:full": "rimraf lib/ app/lib/ app/dist/ app/node_modules/ node_modules/",
+    "clean": "rimraf coverage/ lib/ app/lib/ app/dist/",
+    "clean:full": "rimraf coverage/ lib/ app/lib/ app/dist/ app/node_modules/ node_modules/",
    "lint:fix": "eslint . --ext .ts --fix",
    "lint:format": "prettier --write 'src/**/*.ts' 'app/src/**/*.ts'",
    "lint": "eslint . --ext .ts",
@ -66,7 +66,10 @@
    "yargs": "^17.0.1"
  },
  "devDependencies": {
+    "@types/electron-packager": "^15.0.1",
+    "@types/hasbin": "^1.2.0",
    "@types/jest": "^26.0.23",
+    "@types/loglevel": "^1.6.3",
    "@types/ncp": "^2.0.4",
    "@types/node": "^12.20.15",
    "@types/page-icon": "^0.3.3",
--- a/src/build/buildIcon.ts
+++ b/src/build/buildIcon.ts
@ -45,8 +45,8 @@ export function convertIconIfNecessary(options: AppOptions): void {
      const iconPath = convertToIco(options.packager.icon);
      options.packager.icon = iconPath;
      return;
-    } catch (error) {
-      log.warn('Failed to convert icon to .ico, skipping.', error);
+    } catch (err: unknown) {
+      log.warn('Failed to convert icon to .ico, skipping.', err);
      return;
    }
  }
@ -63,8 +63,8 @@ export function convertIconIfNecessary(options: AppOptions): void {
      const iconPath = convertToPng(options.packager.icon);
      options.packager.icon = iconPath;
      return;
-    } catch (error) {
-      log.warn('Failed to convert icon to .png, skipping.', error);
+    } catch (err: unknown) {
+      log.warn('Failed to convert icon to .png, skipping.', err);
      return;
    }
  }
@ -90,8 +90,8 @@ export function convertIconIfNecessary(options: AppOptions): void {
    if (options.nativefier.tray) {
      convertToTrayIcon(options.packager.icon);
    }
-  } catch (error) {
-    log.warn('Failed to convert icon to .icns, skipping.', error);
+  } catch (err: unknown) {
+    log.warn('Failed to convert icon to .icns, skipping.', err);
    options.packager.icon = undefined;
  }
 }
--- a/src/build/buildNativefierApp.ts
+++ b/src/build/buildNativefierApp.ts
@ -2,18 +2,18 @@ import * as path from 'path';

 import * as electronGet from '@electron/get';
 import * as electronPackager from 'electron-packager';
-import * as hasbin from 'hasbin';
 import * as log from 'loglevel';

 import { convertIconIfNecessary } from './buildIcon';
 import {
  copyFileOrDir,
  getTempDir,
+  hasWine,
  isWindows,
  isWindowsAdmin,
 } from '../helpers/helpers';
 import { useOldAppOptions, findUpgradeApp } from '../helpers/upgrade/upgrade';
-import { AppOptions } from '../options/model';
+import { AppOptions, RawOptions } from '../options/model';
 import { getOptions } from '../options/optionsMain';
 import { prepareElectronApp } from './prepareElectronApp';

@ -70,13 +70,13 @@ async function copyIconsIfNecessary(
 /**
 * Checks the app path array to determine if packaging completed successfully
 */
-function getAppPath(appPath: string | string[]): string {
+function getAppPath(appPath: string | string[]): string | undefined {
  if (!Array.isArray(appPath)) {
    return appPath;
  }

  if (appPath.length === 0) {
-    return null; // directory already exists and `--overwrite` not set
+    return undefined; // directory already exists and `--overwrite` not set
  }

  if (appPath.length > 1) {
@ -89,20 +89,21 @@ function getAppPath(appPath: string | string[]): string {
  return appPath[0];
 }

-function isUpgrade(rawOptions) {
-  return (
+function isUpgrade(rawOptions: RawOptions): boolean {
+  if (
    rawOptions.upgrade !== undefined &&
-    (rawOptions.upgrade === true ||
-      (typeof rawOptions.upgrade === 'string' && rawOptions.upgrade !== ''))
-  );
+    typeof rawOptions.upgrade === 'string' &&
+    rawOptions.upgrade !== ''
+  ) {
+    rawOptions.upgradeFrom = rawOptions.upgrade;
+    rawOptions.upgrade = true;
+    return true;
+  }
+  return false;
 }

 function trimUnprocessableOptions(options: AppOptions): void {
-  if (
-    options.packager.platform === 'win32' &&
-    !isWindows() &&
-    !hasbin.sync('wine')
-  ) {
+  if (options.packager.platform === 'win32' && !isWindows() && !hasWine()) {
    const optionsPresent = Object.entries(options)
      .filter(
        ([key, value]) =>
@ -119,28 +120,30 @@ function trimUnprocessableOptions(options: AppOptions): void {
      'features, like a correct icon and process name. Do yourself a favor and install Wine, please.',
    );
    for (const keyToUnset of optionsPresent) {
-      options[keyToUnset] = null;
+      (options as unknown as Record<string, undefined>)[keyToUnset] = undefined;
    }
  }
 }

 // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
-export async function buildNativefierApp(rawOptions): Promise<string> {
+export async function buildNativefierApp(
+  rawOptions: RawOptions,
+): Promise<string | undefined> {
  log.info('\nProcessing options...');

  if (isUpgrade(rawOptions)) {
-    log.debug('Attempting to upgrade from', rawOptions.upgrade);
-    const oldApp = findUpgradeApp(rawOptions.upgrade.toString());
+    log.debug('Attempting to upgrade from', rawOptions.upgradeFrom);
+    const oldApp = findUpgradeApp(rawOptions.upgradeFrom as string);
    if (oldApp === null) {
      throw new Error(
        `Could not find an old Nativfier app in "${
-          rawOptions.upgrade as string
+          rawOptions.upgradeFrom as string
        }"`,
      );
    }
    rawOptions = useOldAppOptions(rawOptions, oldApp);
    if (rawOptions.out === undefined && rawOptions.overwrite) {
-      rawOptions.out = path.dirname(rawOptions.upgrade);
+      rawOptions.out = path.dirname(rawOptions.upgradeFrom as string);
    }
  }
  log.debug('rawOptions', rawOptions);
--- a/src/build/prepareElectronApp.ts
+++ b/src/build/prepareElectronApp.ts
@ -6,14 +6,15 @@ import { promisify } from 'util';
 import * as log from 'loglevel';

 import { copyFileOrDir, generateRandomSuffix } from '../helpers/helpers';
-import { AppOptions } from '../options/model';
+import { AppOptions, OutputOptions, PackageJSON } from '../options/model';
+import { parseJson } from '../utils/parseUtils';

 const writeFileAsync = promisify(fs.writeFile);

 /**
 * Only picks certain app args to pass to nativefier.json
 */
-function pickElectronAppArgs(options: AppOptions): any {
+function pickElectronAppArgs(options: AppOptions): OutputOptions {
  return {
    accessibilityPrompt: options.nativefier.accessibilityPrompt,
    alwaysOnTop: options.nativefier.alwaysOnTop,
@ -99,7 +100,10 @@ function pickElectronAppArgs(options: AppOptions): any {
  };
 }

-async function maybeCopyScripts(srcs: string[], dest: string): Promise<void> {
+async function maybeCopyScripts(
+  srcs: string[] | undefined,
+  dest: string,
+): Promise<void> {
  if (!srcs || srcs.length === 0) {
    log.debug('No files to inject, skipping copy.');
    return;
@ -151,7 +155,12 @@ function changeAppPackageJsonName(
  url: string,
 ): void {
  const packageJsonPath = path.join(appPath, '/package.json');
-  const packageJson = JSON.parse(fs.readFileSync(packageJsonPath).toString());
+  const packageJson = parseJson<PackageJSON>(
+    fs.readFileSync(packageJsonPath).toString(),
+  );
+  if (!packageJson) {
+    throw new Error(`Could not load package.json from ${packageJsonPath}`);
+  }
  const normalizedAppName = normalizeAppName(name, url);
  packageJson.name = normalizedAppName;
  log.debug(`Updating ${packageJsonPath} 'name' field to ${normalizedAppName}`);
@ -171,10 +180,10 @@ export async function prepareElectronApp(
  log.debug(`Copying electron app from ${src} to ${dest}`);
  try {
    await copyFileOrDir(src, dest);
-  } catch (err) {
-    throw `Error copying electron app from ${src} to temp dir ${dest}. Error: ${(
-      err as Error
-    ).toString()}`;
+  } catch (err: unknown) {
+    throw `Error copying electron app from ${src} to temp dir ${dest}. Error: ${
+      (err as Error).message
+    }`;
  }

  const appJsonPath = path.join(dest, '/nativefier.json');
@ -188,19 +197,19 @@ export async function prepareElectronApp(
    const bookmarksJsonPath = path.join(dest, '/bookmarks.json');
    try {
      await copyFileOrDir(options.nativefier.bookmarksMenu, bookmarksJsonPath);
-    } catch (err) {
+    } catch (err: unknown) {
      log.error('Error copying bookmarks menu config file.', err);
    }
  }

  try {
    await maybeCopyScripts(options.nativefier.inject, dest);
-  } catch (err) {
+  } catch (err: unknown) {
    log.error('Error copying injection files.', err);
  }
  changeAppPackageJsonName(
    dest,
-    options.packager.name,
+    options.packager.name as string,
    options.packager.targetUrl,
  );
 }
--- a/src/cli.test.ts
+++ b/src/cli.test.ts
@ -51,22 +51,22 @@ describe('initArgs + parseArgs', () => {
  test('upgrade arg', () => {
    const args = parseArgs(initArgs(['--upgrade', 'pathToUpgrade']));
    expect(args.upgrade).toBe('pathToUpgrade');
-    expect(args.targetUrl).toBe('');
+    expect(args.targetUrl).toBeUndefined();
  });

  test('upgrade arg with out dir', () => {
    const args = parseArgs(initArgs(['tmp', '--upgrade', 'pathToUpgrade']));
    expect(args.upgrade).toBe('pathToUpgrade');
    expect(args.out).toBe('tmp');
-    expect(args.targetUrl).toBe('');
+    expect(args.targetUrl).toBeUndefined();
  });

  test('upgrade arg with targetUrl', () => {
-    expect(() => {
+    expect(() =>
      parseArgs(
        initArgs(['https://www.google.com', '--upgrade', 'path/to/upgrade']),
-      );
-    }).toThrow();
+      ),
+    ).toThrow();
  });

  test('multi-inject', () => {
@ -92,53 +92,55 @@ describe('initArgs + parseArgs', () => {
  });

  test.each([
-    { arg: 'app-copyright', shortArg: null, value: '(c) Nativefier' },
-    { arg: 'app-version', shortArg: null, value: '2.0.0' },
-    { arg: 'background-color', shortArg: null, value: '#FFAA88' },
-    { arg: 'basic-auth-username', shortArg: null, value: 'user' },
-    { arg: 'basic-auth-password', shortArg: null, value: 'p@ssw0rd' },
-    { arg: 'bookmarks-menu', shortArg: null, value: 'bookmarks.json' },
+    { arg: 'app-copyright', shortArg: '', value: '(c) Nativefier' },
+    { arg: 'app-version', shortArg: '', value: '2.0.0' },
+    { arg: 'background-color', shortArg: '', value: '#FFAA88' },
+    { arg: 'basic-auth-username', shortArg: '', value: 'user' },
+    { arg: 'basic-auth-password', shortArg: '', value: 'p@ssw0rd' },
+    { arg: 'bookmarks-menu', shortArg: '', value: 'bookmarks.json' },
    {
      arg: 'browserwindow-options',
-      shortArg: null,
+      shortArg: '',
      value: '{"test": 456}',
      isJsonString: true,
    },
-    { arg: 'build-version', shortArg: null, value: '3.0.0' },
+    { arg: 'build-version', shortArg: '', value: '3.0.0' },
    {
      arg: 'crash-reporter',
-      shortArg: null,
+      shortArg: '',
      value: 'https://crash-reporter.com',
    },
    { arg: 'electron-version', shortArg: 'e', value: '1.0.0' },
    {
      arg: 'file-download-options',
-      shortArg: null,
+      shortArg: '',
      value: '{"test": 789}',
      isJsonString: true,
    },
-    { arg: 'flash-path', shortArg: null, value: 'pathToFlash' },
-    { arg: 'global-shortcuts', shortArg: null, value: 'shortcuts.json' },
+    { arg: 'flash-path', shortArg: '', value: 'pathToFlash' },
+    { arg: 'global-shortcuts', shortArg: '', value: 'shortcuts.json' },
    { arg: 'icon', shortArg: 'i', value: 'icon.png' },
-    { arg: 'internal-urls', shortArg: null, value: '.*' },
-    { arg: 'lang', shortArg: null, value: 'fr' },
+    { arg: 'internal-urls', shortArg: '', value: '.*' },
+    { arg: 'lang', shortArg: '', value: 'fr' },
    { arg: 'name', shortArg: 'n', value: 'Google' },
    {
      arg: 'process-envs',
-      shortArg: null,
+      shortArg: '',
      value: '{"test": 123}',
      isJsonString: true,
    },
-    { arg: 'proxy-rules', shortArg: null, value: 'RULE: PROXY' },
+    { arg: 'proxy-rules', shortArg: '', value: 'RULE: PROXY' },
    { arg: 'user-agent', shortArg: 'u', value: 'FIREFOX' },
    {
      arg: 'win32metadata',
-      shortArg: null,
+      shortArg: '',
      value: '{"ProductName": "Google"}',
      isJsonString: true,
    },
  ])('test string arg %s', ({ arg, shortArg, value, isJsonString }) => {
-    const args = parseArgs(initArgs(['https://google.com', `--${arg}`, value]));
+    const args = parseArgs(
+      initArgs(['https://google.com', `--${arg}`, value]),
+    ) as Record<string, string>;
    if (!isJsonString) {
      expect(args[arg]).toBe(value);
    } else {
@ -147,8 +149,8 @@ describe('initArgs + parseArgs', () => {

    if (shortArg) {
      const argsShort = parseArgs(
-        initArgs(['https://google.com', `-${shortArg as string}`, value]),
-      );
+        initArgs(['https://google.com', `-${shortArg}`, value]),
+      ) as Record<string, string>;
      if (!isJsonString) {
        expect(argsShort[arg]).toBe(value);
      } else {
@ -162,12 +164,14 @@ describe('initArgs + parseArgs', () => {
    { arg: 'platform', shortArg: 'p', value: 'mac', badValue: 'os2' },
    {
      arg: 'title-bar-style',
-      shortArg: null,
+      shortArg: '',
      value: 'hidden',
      badValue: 'cool',
    },
  ])('limited choice arg %s', ({ arg, shortArg, value, badValue }) => {
-    const args = parseArgs(initArgs(['https://google.com', `--${arg}`, value]));
+    const args = parseArgs(
+      initArgs(['https://google.com', `--${arg}`, value]),
+    ) as Record<string, string>;
    expect(args[arg]).toBe(value);

    // Mock console.error to not pollute the log with the yargs help text
@ -181,7 +185,7 @@ describe('initArgs + parseArgs', () => {
    if (shortArg) {
      const argsShort = parseArgs(
        initArgs(['https://google.com', `-${shortArg}`, value]),
-      );
+      ) as Record<string, string>;
      expect(argsShort[arg]).toBe(value);

      initArgs(['https://google.com', `-${shortArg}`, badValue]);
@ -192,64 +196,74 @@ describe('initArgs + parseArgs', () => {
  });

  test.each([
-    { arg: 'always-on-top', shortArg: null },
-    { arg: 'block-external-urls', shortArg: null },
-    { arg: 'bounce', shortArg: null },
-    { arg: 'clear-cache', shortArg: null },
+    { arg: 'always-on-top', shortArg: '' },
+    { arg: 'block-external-urls', shortArg: '' },
+    { arg: 'bounce', shortArg: '' },
+    { arg: 'clear-cache', shortArg: '' },
    { arg: 'conceal', shortArg: 'c' },
-    { arg: 'counter', shortArg: null },
-    { arg: 'darwin-dark-mode-support', shortArg: null },
-    { arg: 'disable-context-menu', shortArg: null },
-    { arg: 'disable-dev-tools', shortArg: null },
-    { arg: 'disable-gpu', shortArg: null },
-    { arg: 'disable-old-build-warning-yesiknowitisinsecure', shortArg: null },
-    { arg: 'enable-es3-apis', shortArg: null },
+    { arg: 'counter', shortArg: '' },
+    { arg: 'darwin-dark-mode-support', shortArg: '' },
+    { arg: 'disable-context-menu', shortArg: '' },
+    { arg: 'disable-dev-tools', shortArg: '' },
+    { arg: 'disable-gpu', shortArg: '' },
+    { arg: 'disable-old-build-warning-yesiknowitisinsecure', shortArg: '' },
+    { arg: 'enable-es3-apis', shortArg: '' },
    { arg: 'fast-quit', shortArg: 'f' },
-    { arg: 'flash', shortArg: null },
-    { arg: 'full-screen', shortArg: null },
-    { arg: 'hide-window-frame', shortArg: null },
-    { arg: 'honest', shortArg: null },
-    { arg: 'ignore-certificate', shortArg: null },
-    { arg: 'ignore-gpu-blacklist', shortArg: null },
-    { arg: 'insecure', shortArg: null },
-    { arg: 'maximize', shortArg: null },
-    { arg: 'portable', shortArg: null },
+    { arg: 'flash', shortArg: '' },
+    { arg: 'full-screen', shortArg: '' },
+    { arg: 'hide-window-frame', shortArg: '' },
+    { arg: 'honest', shortArg: '' },
+    { arg: 'ignore-certificate', shortArg: '' },
+    { arg: 'ignore-gpu-blacklist', shortArg: '' },
+    { arg: 'insecure', shortArg: '' },
+    { arg: 'maximize', shortArg: '' },
+    { arg: 'portable', shortArg: '' },
    { arg: 'show-menu-bar', shortArg: 'm' },
-    { arg: 'single-instance', shortArg: null },
-    { arg: 'tray', shortArg: null },
-    { arg: 'verbose', shortArg: null },
-    { arg: 'widevine', shortArg: null },
+    { arg: 'single-instance', shortArg: '' },
+    { arg: 'tray', shortArg: '' },
+    { arg: 'verbose', shortArg: '' },
+    { arg: 'widevine', shortArg: '' },
  ])('test boolean arg %s', ({ arg, shortArg }) => {
-    const defaultArgs = parseArgs(initArgs(['https://google.com']));
+    const defaultArgs = parseArgs(initArgs(['https://google.com'])) as Record<
+      string,
+      boolean
+    >;
    expect(defaultArgs[arg]).toBe(false);

-    const args = parseArgs(initArgs(['https://google.com', `--${arg}`]));
+    const args = parseArgs(
+      initArgs(['https://google.com', `--${arg}`]),
+    ) as Record<string, boolean>;
    expect(args[arg]).toBe(true);
    if (shortArg) {
      const argsShort = parseArgs(
        initArgs(['https://google.com', `-${shortArg}`]),
-      );
+      ) as Record<string, boolean>;
      expect(argsShort[arg]).toBe(true);
    }
  });

-  test.each([{ arg: 'no-overwrite', shortArg: null }])(
+  test.each([{ arg: 'no-overwrite', shortArg: '' }])(
    'test inversible boolean arg %s',
    ({ arg, shortArg }) => {
      const inverse = arg.startsWith('no-') ? arg.substr(3) : `no-${arg}`;

-      const defaultArgs = parseArgs(initArgs(['https://google.com']));
+      const defaultArgs = parseArgs(initArgs(['https://google.com'])) as Record<
+        string,
+        boolean
+      >;
      expect(defaultArgs[arg]).toBe(false);
      expect(defaultArgs[inverse]).toBe(true);

-      const args = parseArgs(initArgs(['https://google.com', `--${arg}`]));
+      const args = parseArgs(
+        initArgs(['https://google.com', `--${arg}`]),
+      ) as Record<string, boolean>;
      expect(args[arg]).toBe(true);
      expect(args[inverse]).toBe(false);

      if (shortArg) {
        const argsShort = parseArgs(
-          initArgs(['https://google.com', `-${shortArg as string}`]),
-        );
+          initArgs(['https://google.com', `-${shortArg}`]),
+        ) as Record<string, boolean>;
        expect(argsShort[arg]).toBe(true);
        expect(argsShort[inverse]).toBe(true);
      }
@ -257,35 +271,35 @@ describe('initArgs + parseArgs', () => {
  );

  test.each([
-    { arg: 'disk-cache-size', shortArg: null, value: 100 },
-    { arg: 'height', shortArg: null, value: 200 },
-    { arg: 'max-height', shortArg: null, value: 300 },
-    { arg: 'max-width', shortArg: null, value: 400 },
-    { arg: 'min-height', shortArg: null, value: 500 },
-    { arg: 'min-width', shortArg: null, value: 600 },
-    { arg: 'width', shortArg: null, value: 700 },
-    { arg: 'x', shortArg: null, value: 800 },
-    { arg: 'y', shortArg: null, value: 900 },
+    { arg: 'disk-cache-size', shortArg: '', value: 100 },
+    { arg: 'height', shortArg: '', value: 200 },
+    { arg: 'max-height', shortArg: '', value: 300 },
+    { arg: 'max-width', shortArg: '', value: 400 },
+    { arg: 'min-height', shortArg: '', value: 500 },
+    { arg: 'min-width', shortArg: '', value: 600 },
+    { arg: 'width', shortArg: '', value: 700 },
+    { arg: 'x', shortArg: '', value: 800 },
+    { arg: 'y', shortArg: '', value: 900 },
  ])('test numeric arg %s', ({ arg, shortArg, value }) => {
    const args = parseArgs(
      initArgs(['https://google.com', `--${arg}`, `${value}`]),
-    );
+    ) as Record<string, number>;
    expect(args[arg]).toBe(value);

    const badArgs = parseArgs(
      initArgs(['https://google.com', `--${arg}`, 'abcd']),
-    );
+    ) as Record<string, number>;
    expect(badArgs[arg]).toBeNaN();

    if (shortArg) {
      const shortArgs = parseArgs(
-        initArgs(['https://google.com', `-${shortArg as string}`, `${value}`]),
-      );
+        initArgs(['https://google.com', `-${shortArg}`, `${value}`]),
+      ) as Record<string, number>;
      expect(shortArgs[arg]).toBe(value);

      const badShortArgs = parseArgs(
-        initArgs(['https://google.com', `-${shortArg as string}`, 'abcd']),
-      );
+        initArgs(['https://google.com', `-${shortArg}`, 'abcd']),
+      ) as Record<string, number>;
      expect(badShortArgs[arg]).toBeNaN();
    }
  });
--- a/src/cli.ts
+++ b/src/cli.ts
@ -11,11 +11,12 @@ import {
 } from './helpers/helpers';
 import { supportedArchs, supportedPlatforms } from './infer/inferOs';
 import { buildNativefierApp } from './main';
-import { NativefierOptions } from './options/model';
+import { RawOptions } from './options/model';
 import { parseJson } from './utils/parseUtils';
 import { DEFAULT_ELECTRON_VERSION } from './constants';
+import electronPackager = require('electron-packager');

-export function initArgs(argv: string[]): yargs.Argv<any> {
+export function initArgs(argv: string[]): yargs.Argv<RawOptions> {
  const args = yargs(argv)
    .scriptName('nativefier')
    .usage(
@ -160,7 +161,6 @@ export function initArgs(argv: string[]): yargs.Argv<any> {
      coerce: parseJson,
      description:
        'override Electron BrowserWindow options (via JSON string); see https://github.com/nativefier/nativefier/blob/master/API.md#browserwindow-options',
-      type: 'string',
    })
    .option('disable-context-menu', {
      default: false,
@ -222,7 +222,6 @@ export function initArgs(argv: string[]): yargs.Argv<any> {
      coerce: getProcessEnvs,
      description:
        'a JSON string of key/value pairs to be set as environment variables before any browser windows are opened',
-      type: 'string',
    })
    .option('single-instance', {
      default: false,
@ -285,11 +284,11 @@ export function initArgs(argv: string[]): yargs.Argv<any> {
      coerce: parseJson,
      description:
        'a JSON string defining file download options; see https://github.com/sindresorhus/electron-dl',
-      type: 'string',
    })
    .option('inject', {
      description:
        'path to a CSS/JS file to be injected; pass multiple times to inject multiple files',
+      string: true,
      type: 'array',
    })
    .option('lang', {
@ -477,10 +476,10 @@ export function initArgs(argv: string[]): yargs.Argv<any> {
      type: 'string',
    })
    .option('win32metadata', {
-      coerce: parseJson,
+      coerce: (value: string) =>
+        parseJson<electronPackager.Win32MetadataOptions>(value),
      description:
        '(windows only) a JSON string of key/value pairs (ProductName, InternalName, FileDescription) to embed as executable metadata',
-      type: 'string',
    })
    .group(
      [
@ -526,17 +525,17 @@ function decorateYargOptionGroup(value: string): string {
  return `====== ${value} ======`;
 }

-export function parseArgs(args: yargs.Argv<any>): any {
+export function parseArgs(args: yargs.Argv<RawOptions>): RawOptions {
  const parsed = { ...args.argv };
  // In yargs, the _ property of the parsed args is an array of the positional args
  // https://github.com/yargs/yargs/blob/master/docs/examples.md#and-non-hyphenated-options-too-just-use-argv_
  // So try to extract the targetUrl and outputDirectory from these
-  parsed.targetUrl = parsed._.length > 0 ? parsed._[0].toString() : '';
-  parsed.out = parsed._.length > 1 ? parsed._[1] : '';
+  parsed.targetUrl = parsed._.length > 0 ? parsed._[0].toString() : undefined;
+  parsed.out = parsed._.length > 1 ? (parsed._[1] as string) : undefined;

-  if (parsed.upgrade && parsed.targetUrl !== '') {
+  if (parsed.upgrade && parsed.targetUrl) {
    let targetAndUpgrade = false;
-    if (parsed.out === '') {
+    if (!parsed.out) {
      // If we're upgrading, the first positional args might be the outputDirectory, so swap these if we can
      try {
        // If this succeeds, we have a problem
@ -545,7 +544,7 @@ export function parseArgs(args: yargs.Argv<any>): any {
      } catch {
        // Cool, it's not a URL
        parsed.out = parsed.targetUrl;
-        parsed.targetUrl = '';
+        parsed.targetUrl = undefined;
      }
    } else {
      // Someone supplied a targetUrl, an outputDirectory, and --upgrade. That's not cool.
@ -559,7 +558,7 @@ export function parseArgs(args: yargs.Argv<any>): any {
    }
  }

-  if (parsed.targetUrl === '' && !parsed.upgrade) {
+  if (!parsed.targetUrl && !parsed.upgrade) {
    throw new Error(
      'ERROR: Nativefier must be called with either a targetUrl or the --upgrade option.\n',
    );
@ -572,7 +571,7 @@ export function parseArgs(args: yargs.Argv<any>): any {

 if (require.main === module) {
  // Not sure if we still need this with yargs. Keeping for now.
-  const sanitizedArgs = [];
+  const sanitizedArgs: string[] = [];
  process.argv.forEach((arg) => {
    if (isArgFormatInvalid(arg)) {
      throw new Error(
@ -593,11 +592,12 @@ if (require.main === module) {
    sanitizedArgs.push(arg);
  });

-  let args, parsedArgs;
+  let args: yargs.Argv<RawOptions> | undefined = undefined;
+  let parsedArgs: RawOptions;
  try {
    args = initArgs(sanitizedArgs.slice(2));
    parsedArgs = parseArgs(args);
-  } catch (err) {
+  } catch (err: unknown) {
    if (args) {
      log.error(err);
      args.showHelp();
@ -607,7 +607,7 @@ if (require.main === module) {
    process.exit(1);
  }

-  const options: NativefierOptions = {
+  const options: RawOptions = {
    ...parsedArgs,
  };

--- a/src/helpers/helpers.ts
+++ b/src/helpers/helpers.ts
@ -17,11 +17,17 @@ tmp.setGracefulCleanup(); // cleanup temp dirs even when an uncaught exception o
 const now = new Date();
 const TMP_TIME = `${now.getHours()}-${now.getMinutes()}-${now.getSeconds()}`;

-type DownloadResult = {
+export type DownloadResult = {
  data: Buffer;
  ext: string;
 };

+type ProcessEnvs = Record<string, unknown>;
+
+export function hasWine(): boolean {
+  return hasbin.sync('wine');
+}
+
 export function isOSX(): boolean {
  return os.platform() === 'darwin';
 }
@ -57,7 +63,7 @@ export async function copyFileOrDir(
  dest: string,
 ): Promise<void> {
  return new Promise((resolve, reject) => {
-    ncp(sourceFileOrDir, dest, (error: any) => {
+    ncp(sourceFileOrDir, dest, (error: Error[] | null): void => {
      if (error) {
        reject(error);
      }
@ -66,15 +72,17 @@ export async function copyFileOrDir(
  });
 }

-export function downloadFile(fileUrl: string): Promise<DownloadResult> {
+export function downloadFile(
+  fileUrl: string,
+): Promise<DownloadResult | undefined> {
  log.debug(`Downloading ${fileUrl}`);
  return axios
-    .get(fileUrl, {
+    .get<Buffer>(fileUrl, {
      responseType: 'arraybuffer',
    })
    .then((response) => {
      if (!response.data) {
-        return null;
+        return undefined;
      }
      return {
        data: response.data,
@ -97,7 +105,7 @@ export function getAllowedIconFormats(platform: string): string[] {
  const icnsToPng = false;
  const icnsToIco = false;

-  const formats = [];
+  const formats: string[] = [];

  // Shell scripting is not supported on windows, temporary override
  if (isWindows()) {
@ -175,11 +183,11 @@ export function generateRandomSuffix(length = 6): string {
  return hash.digest('hex').substring(0, length);
 }

-export function getProcessEnvs(val: string): any {
+export function getProcessEnvs(val: string): ProcessEnvs | undefined {
  if (!val) {
-    return {};
+    return undefined;
  }
-  return parseJson(val);
+  return parseJson<ProcessEnvs>(val);
 }

 export function checkInternet(): void {
--- a/src/helpers/upgrade/executableHelpers.ts
+++ b/src/helpers/upgrade/executableHelpers.ts
@ -65,9 +65,9 @@ function getExecutableArch(
 function getExecutableInfo(
  executablePath: string,
  platform: string,
-): ExecutableInfo {
+): ExecutableInfo | undefined {
  if (!fileExists(executablePath)) {
-    return {};
+    return undefined;
  }

  const exeBytes = getExecutableBytes(executablePath);
@ -81,6 +81,12 @@ export function getOptionsFromExecutable(
  priorOptions: NativefierOptions,
 ): NativefierOptions {
  const newOptions: NativefierOptions = { ...priorOptions };
+  if (!newOptions.name) {
+    throw new Error(
+      'Can not extract options from executable with no name specified.',
+    );
+  }
+  const name: string = newOptions.name;
  let executablePath: string | undefined = undefined;

  const appRoot = path.resolve(path.join(appResourcesDir, '..', '..'));
@ -118,8 +124,7 @@ export function getOptionsFromExecutable(
      appRoot,
      children.filter(
        (c) =>
-          c.name.toLowerCase() === `${newOptions.name.toLowerCase()}.exe` &&
-          c.isFile(),
+          c.name.toLowerCase() === `${name.toLowerCase()}.exe` && c.isFile(),
      )[0].name,
    );

@ -130,7 +135,9 @@ export function getOptionsFromExecutable(
        'ProductVersion',
      );
      log.debug(
-        `Extracted app version from executable: ${newOptions.appVersion}`,
+        `Extracted app version from executable: ${
+          newOptions.appVersion as string
+        }`,
      );
    }

@ -142,7 +149,9 @@ export function getOptionsFromExecutable(
        newOptions.buildVersion = undefined;
      } else {
        log.debug(
-          `Extracted build version from executable: ${newOptions.buildVersion}`,
+          `Extracted build version from executable: ${
+            newOptions.buildVersion as string
+          }`,
        );
      }
    }
@ -154,7 +163,9 @@ export function getOptionsFromExecutable(
        'LegalCopyright',
      );
      log.debug(
-        `Extracted app copyright from executable: ${newOptions.appCopyright}`,
+        `Extracted app copyright from executable: ${
+          newOptions.appCopyright as string
+        }`,
      );
    }
  } else if (looksLikeLinux) {
@ -164,7 +175,13 @@ export function getOptionsFromExecutable(
    }
    executablePath = path.join(
      appRoot,
-      children.filter((c) => c.name == newOptions.name && c.isFile())[0].name,
+      children.filter((c) => c.name == name && c.isFile())[0].name,
+    );
+  }
+
+  if (!executablePath || !newOptions.platform) {
+    throw Error(
+      `Could not find executablePath or platform of app in ${appRoot}`,
    );
  }

@ -175,8 +192,14 @@ export function getOptionsFromExecutable(
      executablePath,
      newOptions.platform,
    );
+    if (!executableInfo) {
+      throw new Error(
+        `Could not get executable info for executable path: ${executablePath}`,
+      );
+    }
+
    newOptions.arch = executableInfo.arch;
-    log.debug(`Extracted arch from executable: ${newOptions.arch}`);
+    log.debug(`Extracted arch from executable: ${newOptions.arch as string}`);
  }
  if (newOptions.platform === undefined || newOptions.arch == undefined) {
    throw Error(`Could not determine platform / arch of app in ${appRoot}`);
--- a/src/helpers/upgrade/rceditGet.ts
+++ b/src/helpers/upgrade/rceditGet.ts
@ -8,7 +8,7 @@ import { spawnSync } from 'child_process';
 export function getVersionString(
  executablePath: string,
  versionString: string,
-): string {
+): string | undefined {
  let rcedit = path.resolve(
    __dirname,
    '..',
--- a/src/helpers/upgrade/upgrade.ts
+++ b/src/helpers/upgrade/upgrade.ts
@ -3,10 +3,11 @@ import * as path from 'path';

 import * as log from 'loglevel';

-import { NativefierOptions } from '../../options/model';
+import { NativefierOptions, RawOptions } from '../../options/model';
 import { dirExists, fileExists } from '../fsHelpers';
 import { extractBoolean, extractString } from './plistInfoXMLHelpers';
 import { getOptionsFromExecutable } from './executableHelpers';
+import { parseJson } from '../../utils/parseUtils';

 export type UpgradeAppInfo = {
  appResourcesDir: string;
@ -79,7 +80,9 @@ function getInfoPListOptions(
      'NSHumanReadableCopyright',
    );
    log.debug(
-      `Extracted app copyright from Info.plist: ${newOptions.appCopyright}`,
+      `Extracted app copyright from Info.plist: ${
+        newOptions.appCopyright as string
+      }`,
    );
  }

@ -96,7 +99,9 @@ function getInfoPListOptions(
        ? undefined
        : newOptions.darwinDarkModeSupport === false),
      log.debug(
-        `Extracted app version from Info.plist: ${newOptions.appVersion}`,
+        `Extracted app version from Info.plist: ${
+          newOptions.appVersion as string
+        }`,
      );
  }

@ -152,11 +157,19 @@ export function findUpgradeApp(upgradeFrom: string): UpgradeAppInfo | null {
    return null;
  }

-  log.debug(`Loading ${path.join(appResourcesDir, 'nativefier.json')}`);
-  const options: NativefierOptions = JSON.parse(
-    fs.readFileSync(path.join(appResourcesDir, 'nativefier.json'), 'utf8'),
+  const nativefierJSONPath = path.join(appResourcesDir, 'nativefier.json');
+
+  log.debug(`Loading ${nativefierJSONPath}`);
+  const options = parseJson<NativefierOptions>(
+    fs.readFileSync(nativefierJSONPath, 'utf8'),
  );

+  if (!options) {
+    throw new Error(
+      `Could not read Nativefier options from ${nativefierJSONPath}`,
+    );
+  }
+
  options.electronVersion = undefined;

  return {
@ -173,9 +186,9 @@ export function findUpgradeApp(upgradeFrom: string): UpgradeAppInfo | null {
 }

 export function useOldAppOptions(
-  rawOptions: NativefierOptions,
+  rawOptions: RawOptions,
  oldApp: UpgradeAppInfo,
-): NativefierOptions {
+): RawOptions {
  if (rawOptions.targetUrl !== undefined && dirExists(rawOptions.targetUrl)) {
    // You got your ouput dir in my targetUrl!
    rawOptions.out = rawOptions.targetUrl;
--- a/src/infer/browsers/inferChromeVersion.ts
+++ b/src/infer/browsers/inferChromeVersion.ts
@ -31,7 +31,7 @@ export async function getChromeVersionForElectronVersion(

  try {
    log.debug('Grabbing electron<->chrome versions file from', url);
-    const response = await axios.get(url, { timeout: 5000 });
+    const response = await axios.get<ElectronRelease[]>(url, { timeout: 5000 });
    if (response.status !== 200) {
      throw new Error(`Bad request: Status code ${response.status}`);
    }
@ -50,7 +50,7 @@ export async function getChromeVersionForElectronVersion(
      `Associated electron v${electronVersion} to chrome v${chromeVersion}`,
    );
    return chromeVersion;
-  } catch (err) {
+  } catch (err: unknown) {
    log.error('getChromeVersionForElectronVersion ERROR', err);
    log.debug('Falling back to default Chrome version', DEFAULT_CHROME_VERSION);
    return DEFAULT_CHROME_VERSION;
--- a/src/infer/browsers/inferFirefoxVersion.ts
+++ b/src/infer/browsers/inferFirefoxVersion.ts
@ -28,7 +28,7 @@ export async function getLatestFirefoxVersion(
 ): Promise<string> {
  try {
    log.debug('Grabbing Firefox version data from', url);
-    const response = await axios.get(url, { timeout: 5000 });
+    const response = await axios.get<FirefoxVersions>(url, { timeout: 5000 });
    if (response.status !== 200) {
      throw new Error(`Bad request: Status code ${response.status}`);
    }
@ -38,7 +38,7 @@ export async function getLatestFirefoxVersion(
      `Got latest Firefox version ${firefoxVersions.LATEST_FIREFOX_VERSION}`,
    );
    return firefoxVersions.LATEST_FIREFOX_VERSION;
-  } catch (err) {
+  } catch (err: unknown) {
    log.error('getLatestFirefoxVersion ERROR', err);
    log.debug(
      'Falling back to default Firefox version',
--- a/src/infer/browsers/inferSafariVersion.ts
+++ b/src/infer/browsers/inferSafariVersion.ts
@ -16,7 +16,7 @@ export async function getLatestSafariVersion(
 ): Promise<SafariVersion> {
  try {
    log.debug('Grabbing apple version data from', url);
-    const response = await axios.get(url, { timeout: 5000 });
+    const response = await axios.get<string>(url, { timeout: 5000 });
    if (response.status !== 200) {
      throw new Error(`Bad request: Status code ${response.status}`);
    }
@ -39,8 +39,8 @@ export async function getLatestSafariVersion(

    const versionRows = majorVersionTable.split('<tbody')[1].split('<tr');

-    let version = null;
-    let webkitVersion: string = null;
+    let version: string | undefined = undefined;
+    let webkitVersion: string | undefined = undefined;

    for (const versionRow of versionRows.reverse()) {
      const versionMatch = [
@ -61,12 +61,15 @@ export async function getLatestSafariVersion(
      }
    }

-    return {
-      majorVersion,
-      version,
-      webkitVersion,
-    };
-  } catch (err) {
+    if (version && webkitVersion) {
+      return {
+        majorVersion,
+        version,
+        webkitVersion,
+      };
+    }
+    return DEFAULT_SAFARI_VERSION;
+  } catch (err: unknown) {
    log.error('getLatestSafariVersion ERROR', err);
    log.debug('Falling back to default Safari version', DEFAULT_SAFARI_VERSION);
    return DEFAULT_SAFARI_VERSION;
--- a/src/infer/inferIcon.ts
+++ b/src/infer/inferIcon.ts
@ -7,6 +7,7 @@ import * as pageIcon from 'page-icon';

 import {
  downloadFile,
+  DownloadResult,
  getAllowedIconFormats,
  getTempDir,
 } from '../helpers/helpers';
@ -17,10 +18,17 @@ const writeFileAsync = promisify(writeFile);
 const GITCLOUD_SPACE_DELIMITER = '-';
 const GITCLOUD_URL = 'https://nativefier.github.io/nativefier-icons/';

-function getMaxMatchScore(iconWithScores: any[]): number {
+type GitCloudIcon = {
+  ext?: string;
+  name?: string;
+  score?: number;
+  url?: string;
+};
+
+function getMaxMatchScore(iconWithScores: GitCloudIcon[]): number {
  const score = iconWithScores.reduce((maxScore, currentIcon) => {
    const currentScore = currentIcon.score;
-    if (currentScore > maxScore) {
+    if (currentScore && currentScore > maxScore) {
      return currentScore;
    }
    return maxScore;
@ -29,36 +37,42 @@ function getMaxMatchScore(iconWithScores: any[]): number {
  return score;
 }

-function getMatchingIcons(iconsWithScores: any[], maxScore: number): any[] {
-  return iconsWithScores
-    .filter((item) => item.score === maxScore)
-    .map((item) => ({ ...item, ext: path.extname(item.url) }));
+function getMatchingIcons(
+  iconsWithScores: GitCloudIcon[],
+  maxScore: number,
+): GitCloudIcon[] {
+  return iconsWithScores.filter((item) => item.score === maxScore);
 }

 function mapIconWithMatchScore(
  cloudIcons: { name: string; url: string }[],
  targetUrl: string,
-): any {
+): GitCloudIcon[] {
  const normalisedTargetUrl = targetUrl.toLowerCase();
  return cloudIcons.map((item) => {
    const itemWords = item.name.split(GITCLOUD_SPACE_DELIMITER);
-    const score = itemWords.reduce((currentScore: number, word: string) => {
-      if (normalisedTargetUrl.includes(word)) {
-        return currentScore + 1;
-      }
-      return currentScore;
-    }, 0);
+    const score: number = itemWords.reduce(
+      (currentScore: number, word: string) => {
+        if (normalisedTargetUrl.includes(word)) {
+          return currentScore + 1;
+        }
+        return currentScore;
+      },
+      0,
+    );

-    return { ...item, score };
+    return { ...item, ext: path.extname(item.url), score };
  });
 }

 async function inferIconFromStore(
  targetUrl: string,
  platform: string,
-): Promise<any> {
+): Promise<DownloadResult | undefined> {
  log.debug(`Inferring icon from store for ${targetUrl} on ${platform}`);
-  const allowedFormats = new Set(getAllowedIconFormats(platform));
+  const allowedFormats = new Set<string | undefined>(
+    getAllowedIconFormats(platform),
+  );

  const cloudIcons = await gitCloud(GITCLOUD_URL);
  log.debug(`Got ${cloudIcons.length} icons from gitcloud`);
@ -67,19 +81,19 @@ async function inferIconFromStore(

  if (maxScore === 0) {
    log.debug('No relevant icon in store.');
-    return null;
+    return undefined;
  }

  const iconsMatchingScore = getMatchingIcons(iconWithScores, maxScore);
  const iconsMatchingExt = iconsMatchingScore.filter((icon) =>
-    allowedFormats.has(icon.ext),
+    allowedFormats.has(icon.ext ?? path.extname(icon.url as string)),
  );
  const matchingIcon = iconsMatchingExt[0];
  const iconUrl = matchingIcon && matchingIcon.url;

  if (!iconUrl) {
    log.debug('Could not infer icon from store');
-    return null;
+    return undefined;
  }
  return downloadFile(iconUrl);
 }
@ -87,21 +101,19 @@ async function inferIconFromStore(
 export async function inferIcon(
  targetUrl: string,
  platform: string,
-): Promise<string> {
+): Promise<string | undefined> {
  log.debug(`Inferring icon for ${targetUrl} on ${platform}`);
  const tmpDirPath = getTempDir('iconinfer');

-  let icon: { ext: string; data: Buffer } = await inferIconFromStore(
-    targetUrl,
-    platform,
-  );
+  let icon: { ext: string; data: Buffer } | undefined =
+    await inferIconFromStore(targetUrl, platform);
  if (!icon) {
    const ext = platform === 'win32' ? '.ico' : '.png';
    log.debug(`Trying to extract a ${ext} icon from the page.`);
    icon = await pageIcon(targetUrl, { ext });
  }
  if (!icon) {
-    return null;
+    return undefined;
  }
  log.debug(`Got an icon from the page.`);

--- a/src/infer/inferOs.ts
+++ b/src/infer/inferOs.ts
@ -19,13 +19,7 @@ export const supportedPlatforms = [

 export function inferPlatform(): string {
  const platform = os.platform();
-  if (
-    platform === 'darwin' ||
-    // @ts-ignore
-    platform === 'mas' ||
-    platform === 'win32' ||
-    platform === 'linux'
-  ) {
+  if (['darwin', 'linux', 'win32'].includes(platform)) {
    log.debug('Inferred platform', platform);
    return platform;
  }
--- a/src/infer/inferTitle.ts
+++ b/src/infer/inferTitle.ts
@ -5,7 +5,7 @@ const USER_AGENT =
  'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2227.1 Safari/537.36';

 export async function inferTitle(url: string): Promise<string> {
-  const { data } = await axios.get(url, {
+  const { data } = await axios.get<string>(url, {
    headers: {
      // Fake user agent for pages like http://messenger.com
      'User-Agent': USER_AGENT,
@ -13,7 +13,7 @@ export async function inferTitle(url: string): Promise<string> {
  });
  log.debug(`Fetched ${(data.length / 1024).toFixed(1)} kb page at`, url);
  const inferredTitle =
-    /<\s*title.*?>(?<title>.+?)<\s*\/title\s*?>/i.exec(data).groups?.title ||
+    /<\s*title.*?>(?<title>.+?)<\s*\/title\s*?>/i.exec(data)?.groups?.title ??
    'Webapp';
  log.debug('Inferred title:', inferredTitle);
  return inferredTitle;
--- a/src/integration-test.ts
+++ b/src/integration-test.ts
@ -10,9 +10,14 @@ import { getLatestSafariVersion } from './infer/browsers/inferSafariVersion';
 import { inferArch } from './infer/inferOs';
 import { buildNativefierApp } from './main';
 import { userAgent } from './options/fields/userAgent';
+import { NativefierOptions } from './options/model';
+import { parseJson } from './utils/parseUtils';

-async function checkApp(appRoot: string, inputOptions: any): Promise<void> {
-  const arch = (inputOptions.arch as string) || inferArch();
+async function checkApp(
+  appRoot: string,
+  inputOptions: NativefierOptions,
+): Promise<void> {
+  const arch = inputOptions.arch ? (inputOptions.arch as string) : inferArch();
  if (inputOptions.out !== undefined) {
    expect(
      path.join(
@ -43,28 +48,31 @@ async function checkApp(appRoot: string, inputOptions: any): Promise<void> {
  const appPath = path.join(appRoot, relativeAppFolder);

  const configPath = path.join(appPath, 'nativefier.json');
-  const nativefierConfig = JSON.parse(fs.readFileSync(configPath).toString());
-  expect(inputOptions.targetUrl).toBe(nativefierConfig.targetUrl);
+  const nativefierConfig: NativefierOptions | undefined =
+    parseJson<NativefierOptions>(fs.readFileSync(configPath).toString());
+  expect(nativefierConfig).not.toBeUndefined();
+
+  expect(inputOptions.targetUrl).toBe(nativefierConfig?.targetUrl);

  // Test name inferring
-  expect(nativefierConfig.name).toBe('Google');
+  expect(nativefierConfig?.name).toBe('Google');

  // Test icon writing
  const iconFile =
    inputOptions.platform === 'darwin' ? '../electron.icns' : 'icon.png';
  const iconPath = path.join(appPath, iconFile);
-  expect(fs.existsSync(iconPath)).toBe(true);
+  expect(fs.existsSync(iconPath)).toEqual(true);
  expect(fs.statSync(iconPath).size).toBeGreaterThan(1000);

  // Test arch
  if (inputOptions.arch !== undefined) {
-    expect(inputOptions.arch).toBe(nativefierConfig.arch);
+    expect(inputOptions.arch).toEqual(nativefierConfig?.arch);
  } else {
-    expect(os.arch()).toBe(nativefierConfig.arch);
+    expect(os.arch()).toEqual(nativefierConfig?.arch);
  }

  // Test electron version
-  expect(nativefierConfig.electronVersionUsed).toBe(
+  expect(nativefierConfig?.electronVersionUsed).toBe(
    inputOptions.electronVersion || DEFAULT_ELECTRON_VERSION,
  );

@ -80,10 +88,11 @@ async function checkApp(appRoot: string, inputOptions: any): Promise<void> {
    });
    inputOptions.userAgent = translatedUserAgent || inputOptions.userAgent;
  }
-  expect(nativefierConfig.userAgent).toBe(inputOptions.userAgent);
+
+  expect(nativefierConfig?.userAgent).toEqual(inputOptions.userAgent);

  // Test lang
-  expect(nativefierConfig.lang).toBe(inputOptions.lang);
+  expect(nativefierConfig?.lang).toEqual(inputOptions.lang);
 }

 describe('Nativefier', () => {
@ -101,7 +110,8 @@ describe('Nativefier', () => {
        lang: 'en-US',
      };
      const appPath = await buildNativefierApp(options);
-      await checkApp(appPath, options);
+      expect(appPath).not.toBeUndefined();
+      await checkApp(appPath as string, options);
    },
  );
 });
@ -132,7 +142,8 @@ describe('Nativefier upgrade', () => {
        ...baseAppOptions,
      };
      const appPath = await buildNativefierApp(options);
-      await checkApp(appPath, options);
+      expect(appPath).not.toBeUndefined();
+      await checkApp(appPath as string, options);

      const upgradeOptions = {
        upgrade: appPath,
@ -142,7 +153,8 @@ describe('Nativefier upgrade', () => {
      const upgradeAppPath = await buildNativefierApp(upgradeOptions);
      options.electronVersion = DEFAULT_ELECTRON_VERSION;
      options.userAgent = baseAppOptions.userAgent;
-      await checkApp(upgradeAppPath, options);
+      expect(upgradeAppPath).not.toBeUndefined();
+      await checkApp(upgradeAppPath as string, options);
    },
  );
 });
--- a/src/main.ts
+++ b/src/main.ts
@ -1,6 +1,7 @@
 import 'source-map-support/register';

 import { buildNativefierApp } from './build/buildNativefierApp';
+import { RawOptions } from './options/model';

 export { buildNativefierApp };

@ -9,12 +10,12 @@ export { buildNativefierApp };
 * Use the better, modern async `buildNativefierApp` instead if you can!
 */
 function buildNativefierAppOldCallbackStyle(
-  options: any, // eslint-disable-line @typescript-eslint/explicit-module-boundary-types
-  callback: (err: any, result?: any) => void,
+  options: RawOptions, // eslint-disable-line @typescript-eslint/explicit-module-boundary-types
+  callback: (err?: Error, result?: string) => void,
 ): void {
  buildNativefierApp(options)
-    .then((result) => callback(null, result))
-    .catch((err) => callback(err));
+    .then((result) => callback(undefined, result))
+    .catch((err: Error) => callback(err));
 }

 export default buildNativefierAppOldCallbackStyle;
--- a/src/options/asyncConfig.ts
+++ b/src/options/asyncConfig.ts
@ -6,7 +6,7 @@ import { AppOptions } from './model';
 /**
 * Takes the options object and infers new values needing async work
 */
-export async function asyncConfig(options: AppOptions): Promise<any> {
+export async function asyncConfig(options: AppOptions): Promise<AppOptions> {
  log.debug('\nPerforming async options post-processing.');
-  await processOptions(options);
+  return await processOptions(options);
 }
--- a/src/options/fields/fields.test.ts
+++ b/src/options/fields/fields.test.ts
@ -1,53 +1,103 @@
+import { AppOptions } from '../model';
 import { processOptions } from './fields';
+describe('fields', () => {
+  let options: AppOptions;

-test('fully-defined async options are returned as-is', async () => {
-  const options = {
-    packager: {
-      icon: '/my/icon.png',
-      name: 'my beautiful app ',
-      targetUrl: 'https://myurl.com',
-      dir: '/tmp/myapp',
-    },
-    nativefier: { userAgent: 'random user agent' },
-  };
-  // @ts-ignore
-  await processOptions(options);
+  beforeEach(() => {
+    options = {
+      nativefier: {
+        accessibilityPrompt: false,
+        alwaysOnTop: false,
+        backgroundColor: undefined,
+        basicAuthPassword: undefined,
+        basicAuthUsername: undefined,
+        blockExternalUrls: false,
+        bookmarksMenu: undefined,
+        bounce: false,
+        browserwindowOptions: undefined,
+        clearCache: false,
+        counter: false,
+        crashReporter: undefined,
+        disableContextMenu: false,
+        disableDevTools: false,
+        disableGpu: false,
+        disableOldBuildWarning: false,
+        diskCacheSize: undefined,
+        enableEs3Apis: false,
+        fastQuit: true,
+        fileDownloadOptions: undefined,
+        flashPluginDir: undefined,
+        fullScreen: false,
+        globalShortcuts: undefined,
+        height: undefined,
+        hideWindowFrame: false,
+        ignoreCertificate: false,
+        ignoreGpuBlacklist: false,
+        inject: [],
+        insecure: false,
+        internalUrls: undefined,
+        maximize: false,
+        maxHeight: undefined,
+        minWidth: undefined,
+        minHeight: undefined,
+        maxWidth: undefined,
+        nativefierVersion: '1.0.0',
+        processEnvs: undefined,
+        proxyRules: undefined,
+        showMenuBar: false,
+        singleInstance: false,
+        titleBarStyle: undefined,
+        tray: false,
+        userAgent: undefined,
+        userAgentHonest: false,
+        verbose: false,
+        versionString: '1.0.0',
+        width: undefined,
+        widevine: false,
+        x: undefined,
+        y: undefined,
+        zoom: 1,
+      },
+      packager: {
+        dir: '',
+        platform: process.platform,
+        portable: false,
+        targetUrl: '',
+        upgrade: false,
+      },
+    };
+  });

-  expect(options.packager.icon).toEqual('/my/icon.png');
-  expect(options.packager.name).toEqual('my beautiful app');
-  expect(options.nativefier.userAgent).toEqual('random user agent');
-});
-
-test('user agent is ignored if not provided', async () => {
-  const options = {
-    packager: {
-      icon: '/my/icon.png',
-      name: 'my beautiful app ',
-      targetUrl: 'https://myurl.com',
-      dir: '/tmp/myapp',
-      platform: 'linux',
-    },
-    nativefier: { userAgent: undefined },
-  };
-  // @ts-ignore
-  await processOptions(options);
-
-  expect(options.nativefier.userAgent).toBeUndefined();
-});
-
-test('user agent short code is populated', async () => {
-  const options = {
-    packager: {
-      icon: '/my/icon.png',
-      name: 'my beautiful app ',
-      targetUrl: 'https://myurl.com',
-      dir: '/tmp/myapp',
-      platform: 'linux',
-    },
-    nativefier: { userAgent: 'edge' },
-  };
-  // @ts-ignore
-  await processOptions(options);
-
-  expect(options.nativefier.userAgent).not.toBe('edge');
+  test('fully-defined async options are returned as-is', async () => {
+    options.packager.icon = '/my/icon.png';
+    options.packager.name = 'my beautiful app ';
+    options.packager.platform = 'darwin';
+    options.nativefier.userAgent = 'random user agent';
+    await processOptions(options);
+
+    expect(options.packager.icon).toEqual('/my/icon.png');
+    expect(options.packager.name).toEqual('my beautiful app');
+    expect(options.nativefier.userAgent).toEqual('random user agent');
+  });
+
+  test('name has spaces stripped in linux', async () => {
+    options.packager.name = 'my beautiful app ';
+    options.packager.platform = 'linux';
+    await processOptions(options);
+
+    expect(options.packager.name).toEqual('mybeautifulapp');
+  });
+
+  test('user agent is ignored if not provided', async () => {
+    await processOptions(options);
+
+    expect(options.nativefier.userAgent).toBeUndefined();
+  });
+
+  test('user agent short code is populated', async () => {
+    options.nativefier.userAgent = 'edge';
+    await processOptions(options);
+
+    expect(options.nativefier.userAgent).not.toBe('edge');
+  });
 });
--- a/src/options/fields/fields.ts
+++ b/src/options/fields/fields.ts
@ -3,13 +3,19 @@ import { userAgent } from './userAgent';
 import { AppOptions } from '../model';
 import { name } from './name';

-const OPTION_POSTPROCESSORS = [
+type OptionPostprocessor = {
+  namespace: 'nativefier' | 'packager';
+  option: 'icon' | 'name' | 'userAgent';
+  processor: (options: AppOptions) => Promise<string | undefined>;
+};
+
+const OPTION_POSTPROCESSORS: OptionPostprocessor[] = [
  { namespace: 'nativefier', option: 'userAgent', processor: userAgent },
  { namespace: 'packager', option: 'icon', processor: icon },
  { namespace: 'packager', option: 'name', processor: name },
 ];

-export async function processOptions(options: AppOptions): Promise<void> {
+export async function processOptions(options: AppOptions): Promise<AppOptions> {
  const processedOptions = await Promise.all(
    OPTION_POSTPROCESSORS.map(async ({ namespace, option, processor }) => {
      const result = await processor(options);
@ -22,8 +28,15 @@ export async function processOptions(options: AppOptions): Promise<void> {
  );

  for (const { namespace, option, result } of processedOptions) {
-    if (result !== null) {
+    if (
+      result &&
+      namespace in options &&
+      options[namespace] &&
+      option in options[namespace]
+    ) {
+      // @ts-expect-error We're fiddling with objects at the string key level, which TS doesn't support well.
      options[namespace][option] = result;
    }
  }
+  return options;
 }
--- a/src/options/fields/icon.test.ts
+++ b/src/options/fields/icon.test.ts
@ -24,7 +24,7 @@ const ICON_PARAMS_NEEDS_INFER = {
 describe('when the icon parameter is passed', () => {
  test('it should return the icon parameter', async () => {
    expect(inferIcon).toHaveBeenCalledTimes(0);
-    await expect(icon(ICON_PARAMS_PROVIDED)).resolves.toBe(null);
+    await expect(icon(ICON_PARAMS_PROVIDED)).resolves.toBeUndefined();
  });
 });

@ -49,7 +49,7 @@ describe('when the icon parameter is not passed', () => {
      );
      const result = await icon(ICON_PARAMS_NEEDS_INFER);

-      expect(result).toBe(null);
+      expect(result).toBeUndefined();
      expect(inferIcon).toHaveBeenCalledWith(
        ICON_PARAMS_NEEDS_INFER.packager.targetUrl,
        ICON_PARAMS_NEEDS_INFER.packager.platform,
--- a/src/options/fields/icon.ts
+++ b/src/options/fields/icon.ts
@ -10,10 +10,15 @@ type IconParams = {
  };
 };

-export async function icon(options: IconParams): Promise<string> {
+export async function icon(options: IconParams): Promise<string | undefined> {
  if (options.packager.icon) {
    log.debug('Got icon from options. Using it, no inferring needed');
-    return null;
+    return undefined;
+  }
+
+  if (!options.packager.platform) {
+    log.error('No platform specified. Icon can not be inferrerd.');
+    return undefined;
  }

  try {
@ -21,11 +26,8 @@ export async function icon(options: IconParams): Promise<string> {
      options.packager.targetUrl,
      options.packager.platform,
    );
-  } catch (error) {
-    log.warn(
-      'Cannot automatically retrieve the app icon:',
-      error.message || '',
-    );
-    return null;
+  } catch (err: unknown) {
+    log.warn('Cannot automatically retrieve the app icon:', err);
+    return undefined;
  }
 }
--- a/src/options/fields/name.ts
+++ b/src/options/fields/name.ts
@ -17,24 +17,20 @@ async function tryToInferName(targetUrl: string): Promise<string> {
    log.debug('Inferring name for', targetUrl);
    const pageTitle = await inferTitle(targetUrl);
    return pageTitle || DEFAULT_APP_NAME;
-  } catch (err) {
+  } catch (err: unknown) {
    log.warn(
-      `Unable to automatically determine app name, falling back to '${DEFAULT_APP_NAME}'. Reason: ${(
-        err as Error
-      ).toString()}`,
+      `Unable to automatically determine app name, falling back to '${DEFAULT_APP_NAME}'.`,
+      err,
    );
    return DEFAULT_APP_NAME;
  }
 }

 export async function name(options: NameParams): Promise<string> {
-  if (options.packager.name) {
-    log.debug(
-      `Got name ${options.packager.name} from options. No inferring needed`,
-    );
-    return sanitizeFilename(options.packager.platform, options.packager.name);
+  let name: string | undefined = options.packager.name;
+  if (!name) {
+    name = await tryToInferName(options.packager.targetUrl);
  }

-  const inferredName = await tryToInferName(options.packager.targetUrl);
-  return sanitizeFilename(options.packager.platform, inferredName);
+  return sanitizeFilename(options.packager.platform, name);
 }
--- a/src/options/fields/userAgent.test.ts
+++ b/src/options/fields/userAgent.test.ts
@ -12,7 +12,7 @@ test('when a userAgent parameter is passed', async () => {
    packager: {},
    nativefier: { userAgent: 'valid user agent' },
  };
-  await expect(userAgent(params)).resolves.toBeNull();
+  await expect(userAgent(params)).resolves.toBeUndefined();
 });

 test('no userAgent parameter is passed', async () => {
@ -20,7 +20,7 @@ test('no userAgent parameter is passed', async () => {
    packager: { platform: 'mac' },
    nativefier: {},
  };
-  await expect(userAgent(params)).resolves.toBeNull();
+  await expect(userAgent(params)).resolves.toBeUndefined();
 });

 test('edge userAgent parameter is passed', async () => {
--- a/src/options/fields/userAgent.ts
+++ b/src/options/fields/userAgent.ts
@ -1,11 +1,12 @@
 import * as log from 'loglevel';
+import { DEFAULT_ELECTRON_VERSION } from '../../constants';

 import { getChromeVersionForElectronVersion } from '../../infer/browsers/inferChromeVersion';
 import { getLatestFirefoxVersion } from '../../infer/browsers/inferFirefoxVersion';
 import { getLatestSafariVersion } from '../../infer/browsers/inferSafariVersion';
 import { normalizePlatform } from '../optionsMain';

-type UserAgentOpts = {
+export type UserAgentOpts = {
  packager: {
    electronVersion?: string;
    platform?: string;
@ -15,22 +16,27 @@ type UserAgentOpts = {
  };
 };

-const USER_AGENT_PLATFORM_MAPS = {
+const USER_AGENT_PLATFORM_MAPS: Record<string, string> = {
  darwin: 'Macintosh; Intel Mac OS X 10_15_7',
  linux: 'X11; Linux x86_64',
  win32: 'Windows NT 10.0; Win64; x64',
 };

-const USER_AGENT_SHORT_CODE_MAPS = {
+const USER_AGENT_SHORT_CODE_MAPS: Record<
+  string,
+  (platform: string, electronVersion: string) => Promise<string>
+> = {
  edge: edgeUserAgent,
  firefox: firefoxUserAgent,
  safari: safariUserAgent,
 };

-export async function userAgent(options: UserAgentOpts): Promise<string> {
+export async function userAgent(
+  options: UserAgentOpts,
+): Promise<string | undefined> {
  if (!options.nativefier.userAgent) {
    // No user agent got passed. Let's handle it with the app.userAgentFallback
-    return null;
+    return undefined;
  }

  if (
@ -43,19 +49,22 @@ export async function userAgent(options: UserAgentOpts): Promise<string> {
      `${options.nativefier.userAgent.toLowerCase()} not found in`,
      Object.keys(USER_AGENT_SHORT_CODE_MAPS),
    );
-    return null;
+    return undefined;
  }

  options.packager.platform = normalizePlatform(options.packager.platform);

-  const userAgentPlatform =
+  const userAgentPlatform: string =
    USER_AGENT_PLATFORM_MAPS[
      options.packager.platform === 'mas' ? 'darwin' : options.packager.platform
    ];

  const mapFunction = USER_AGENT_SHORT_CODE_MAPS[options.nativefier.userAgent];

-  return await mapFunction(userAgentPlatform, options.packager.electronVersion);
+  return await mapFunction(
+    userAgentPlatform,
+    options.packager.electronVersion ?? DEFAULT_ELECTRON_VERSION,
+  );
 }

 async function edgeUserAgent(
--- a/src/options/model.ts
+++ b/src/options/model.ts
@ -1,8 +1,9 @@
+import { CreateOptions } from 'asar';
 import * as electronPackager from 'electron-packager';

 export interface ElectronPackagerOptions extends electronPackager.Options {
  portable: boolean;
-  platform: string;
+  platform?: string;
  targetUrl: string;
  upgrade: boolean;
  upgradeFrom?: string;
@ -13,60 +14,152 @@ export interface AppOptions {
  nativefier: {
    accessibilityPrompt: boolean;
    alwaysOnTop: boolean;
-    backgroundColor: string;
-    basicAuthPassword: string;
-    basicAuthUsername: string;
+    backgroundColor?: string;
+    basicAuthPassword?: string;
+    basicAuthUsername?: string;
    blockExternalUrls: boolean;
-    bookmarksMenu: string;
+    bookmarksMenu?: string;
    bounce: boolean;
-    browserwindowOptions: any;
+    browserwindowOptions?: BrowserWindowOptions;
    clearCache: boolean;
    counter: boolean;
-    crashReporter: string;
+    crashReporter?: string;
    disableContextMenu: boolean;
    disableDevTools: boolean;
    disableGpu: boolean;
    disableOldBuildWarning: boolean;
-    diskCacheSize: number;
+    diskCacheSize?: number;
    electronVersionUsed?: string;
    enableEs3Apis: boolean;
    fastQuit: boolean;
-    fileDownloadOptions: any;
-    flashPluginDir: string;
+    fileDownloadOptions: unknown;
+    flashPluginDir?: string;
    fullScreen: boolean;
-    globalShortcuts: any;
+    globalShortcuts?: GlobalShortcut[];
    hideWindowFrame: boolean;
    ignoreCertificate: boolean;
    ignoreGpuBlacklist: boolean;
-    inject: string[];
+    inject?: string[];
    insecure: boolean;
-    internalUrls: string;
+    internalUrls?: string;
    lang?: string;
    maximize: boolean;
-    nativefierVersion: string;
-    processEnvs: string;
-    proxyRules: string;
+    nativefierVersion?: string;
+    processEnvs?: string;
+    proxyRules?: string;
    showMenuBar: boolean;
    singleInstance: boolean;
-    titleBarStyle: string;
+    titleBarStyle?: string;
    tray: string | boolean;
-    userAgent: string;
+    userAgent?: string;
    userAgentHonest: boolean;
    verbose: boolean;
-    versionString: string;
-    width: number;
+    versionString?: string;
+    width?: number;
    widevine: boolean;
-    height: number;
-    minWidth: number;
-    minHeight: number;
-    maxWidth: number;
-    maxHeight: number;
-    x: number;
-    y: number;
+    height?: number;
+    minWidth?: number;
+    minHeight?: number;
+    maxWidth?: number;
+    maxHeight?: number;
+    x?: number;
+    y?: number;
    zoom: number;
  };
 }

+export type BrowserWindowOptions = Record<string, unknown>;
+
+export type GlobalShortcut = {
+  key: string;
+};
+
 export type NativefierOptions = Partial<
  AppOptions['packager'] & AppOptions['nativefier']
 >;
+
+export type OutputOptions = NativefierOptions & {
+  buildDate: number;
+  isUpgrade: boolean;
+  oldBuildWarningText: string;
+};
+
+export type PackageJSON = {
+  name: string;
+};
+
+export type RawOptions = {
+  accessibilityPrompt?: boolean;
+  alwaysOnTop?: boolean;
+  appCopyright?: string;
+  appVersion?: string;
+  arch?: string | string[];
+  asar?: boolean | CreateOptions;
+  backgroundColor?: string;
+  basicAuthPassword?: string;
+  basicAuthUsername?: string;
+  blockExternalUrls?: boolean;
+  bookmarksMenu?: string;
+  bounce?: boolean;
+  browserwindowOptions?: BrowserWindowOptions;
+  buildVersion?: string;
+  clearCache?: boolean;
+  conceal?: boolean;
+  counter?: boolean;
+  crashReporter?: string;
+  darwinDarkModeSupport?: boolean;
+  disableContextMenu?: boolean;
+  disableDevTools?: boolean;
+  disableGpu?: boolean;
+  disableOldBuildWarning?: boolean;
+  disableOldBuildWarningYesiknowitisinsecure?: boolean;
+  diskCacheSize?: number;
+  electronVersion?: string;
+  electronVersionUsed?: string;
+  enableEs3Apis?: boolean;
+  fastQuit?: boolean;
+  fileDownloadOptions?: unknown;
+  flashPath?: string;
+  flashPluginDir?: string;
+  fullScreen?: boolean;
+  globalShortcuts?: string | GlobalShortcut[];
+  height?: number;
+  hideWindowFrame?: boolean;
+  icon?: string;
+  ignoreCertificate?: boolean;
+  ignoreGpuBlacklist?: boolean;
+  inject?: string[];
+  insecure?: boolean;
+  internalUrls?: string;
+  lang?: string;
+  maxHeight?: number;
+  maximize?: boolean;
+  maxWidth?: number;
+  minHeight?: number;
+  minWidth?: number;
+  name?: string;
+  nativefierVersion?: string;
+  out?: string;
+  overwrite?: boolean;
+  platform?: string;
+  portable?: boolean;
+  processEnvs?: string;
+  proxyRules?: string;
+  showMenuBar?: boolean;
+  singleInstance?: boolean;
+  targetUrl?: string;
+  titleBarStyle?: string;
+  tray?: string | boolean;
+  upgrade?: string | boolean;
+  upgradeFrom?: string;
+  userAgent?: string;
+  userAgentHonest?: boolean;
+  verbose?: boolean;
+  versionString?: string;
+  widevine?: boolean;
+  width?: number;
+  win32metadata?: electronPackager.Win32MetadataOptions;
+  x?: number;
+  y?: number;
+  zoom?: number;
+};
--- a/src/options/normalizeUrl.ts
+++ b/src/options/normalizeUrl.ts
@ -22,8 +22,9 @@ export function normalizeUrl(urlToNormalize: string): string {
  let parsedUrl: url.URL;
  try {
    parsedUrl = new url.URL(urlWithProtocol);
-  } catch (err) {
-    throw `Your url "${urlWithProtocol}" is invalid`;
+  } catch (err: unknown) {
+    log.error('normalizeUrl ERROR', err);
+    throw new Error(`Your url "${urlWithProtocol}" is invalid`);
  }
  const normalizedUrl = parsedUrl.toString();
  log.debug(`Normalized URL ${urlToNormalize} to:`, normalizedUrl);
--- a/src/options/optionsMain.test.ts
+++ b/src/options/optionsMain.test.ts
@ -1,9 +1,71 @@
 import { getOptions, normalizePlatform } from './optionsMain';
 import * as asyncConfig from './asyncConfig';
 import { inferPlatform } from '../infer/inferOs';
+import { AppOptions } from './model';

-const mockedAsyncConfig = { some: 'options' };
 let asyncConfigMock: jest.SpyInstance;
+const mockedAsyncConfig: AppOptions = {
+  nativefier: {
+    accessibilityPrompt: false,
+    alwaysOnTop: false,
+    backgroundColor: undefined,
+    basicAuthPassword: undefined,
+    basicAuthUsername: undefined,
+    blockExternalUrls: false,
+    bookmarksMenu: undefined,
+    bounce: false,
+    browserwindowOptions: undefined,
+    clearCache: false,
+    counter: false,
+    crashReporter: undefined,
+    disableContextMenu: false,
+    disableDevTools: false,
+    disableGpu: false,
+    disableOldBuildWarning: false,
+    diskCacheSize: undefined,
+    enableEs3Apis: false,
+    fastQuit: true,
+    fileDownloadOptions: undefined,
+    flashPluginDir: undefined,
+    fullScreen: false,
+    globalShortcuts: undefined,
+    height: undefined,
+    hideWindowFrame: false,
+    ignoreCertificate: false,
+    ignoreGpuBlacklist: false,
+    inject: [],
+    insecure: false,
+    internalUrls: undefined,
+    maximize: false,
+    maxHeight: undefined,
+    minWidth: undefined,
+    minHeight: undefined,
+    maxWidth: undefined,
+    nativefierVersion: '1.0.0',
+    processEnvs: undefined,
+    proxyRules: undefined,
+    showMenuBar: false,
+    singleInstance: false,
+    titleBarStyle: undefined,
+    tray: false,
+    userAgent: undefined,
+    userAgentHonest: false,
+    verbose: false,
+    versionString: '1.0.0',
+    width: undefined,
+    widevine: false,
+    x: undefined,
+    y: undefined,
+    zoom: 1,
+  },
+  packager: {
+    dir: '',
+    platform: process.platform,
+    portable: false,
+    targetUrl: '',
+    upgrade: false,
+  },
+};

 beforeAll(() => {
  asyncConfigMock = jest
@ -18,8 +80,8 @@ test('it should call the async config', async () => {
  const result = await getOptions(params);
  expect(asyncConfigMock).toHaveBeenCalledWith(
    expect.objectContaining({
-      packager: expect.anything(),
-      nativefier: expect.anything(),
+      packager: expect.anything() as AppOptions['packager'],
+      nativefier: expect.anything() as AppOptions['nativefier'],
    }),
  );
  expect(result.packager.targetUrl).toEqual(params.targetUrl);
@ -34,7 +96,7 @@ test('it should set the accessibility prompt option to true by default', async (
    expect.objectContaining({
      nativefier: expect.objectContaining({
        accessibilityPrompt: true,
-      }),
+      }) as AppOptions['nativefier'],
    }),
  );
  expect(result.nativefier.accessibilityPrompt).toEqual(true);
--- a/src/options/optionsMain.ts
+++ b/src/options/optionsMain.ts
@ -1,11 +1,17 @@
 import * as fs from 'fs';

 import axios from 'axios';
+import * as debug from 'debug';
 import * as log from 'loglevel';

 // package.json is `require`d to let tsc strip the `src` folder by determining
 // baseUrl=src. A static import would prevent that and cause an ugly extra `src` folder in `lib`
-const packageJson = require('../../package.json'); // eslint-disable-line @typescript-eslint/no-var-requires
+// eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+const packageJson: {
+  name: string;
+  version: string;
+  // eslint-disable-next-line @typescript-eslint/no-var-requires
+} = require('../../package.json');
 import {
  DEFAULT_ELECTRON_VERSION,
  PLACEHOLDER_APP_DIR,
@ -13,8 +19,9 @@ import {
 } from '../constants';
 import { inferPlatform, inferArch } from '../infer/inferOs';
 import { asyncConfig } from './asyncConfig';
-import { AppOptions } from './model';
+import { AppOptions, GlobalShortcut, RawOptions } from './model';
 import { normalizeUrl } from './normalizeUrl';
+import { parseJson } from '../utils/parseUtils';

 const SEMVER_VERSION_NUMBER_REGEX = /\d+\.\d+\.\d+[-_\w\d.]*/;

@ -22,31 +29,33 @@ const SEMVER_VERSION_NUMBER_REGEX = /\d+\.\d+\.\d+[-_\w\d.]*/;
 * Process and validate raw user arguments
 */
 // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
-export async function getOptions(rawOptions: any): Promise<AppOptions> {
+export async function getOptions(rawOptions: RawOptions): Promise<AppOptions> {
  const options: AppOptions = {
    packager: {
      appCopyright: rawOptions.appCopyright,
      appVersion: rawOptions.appVersion,
-      arch: rawOptions.arch || inferArch(),
-      asar: rawOptions.asar || rawOptions.conceal || false,
+      arch: rawOptions.arch ?? inferArch(),
+      asar: rawOptions.asar ?? rawOptions.conceal ?? false,
      buildVersion: rawOptions.buildVersion,
-      darwinDarkModeSupport: rawOptions.darwinDarkModeSupport || false,
+      darwinDarkModeSupport: rawOptions.darwinDarkModeSupport ?? false,
      dir: PLACEHOLDER_APP_DIR,
-      electronVersion: rawOptions.electronVersion || DEFAULT_ELECTRON_VERSION,
+      electronVersion: rawOptions.electronVersion ?? DEFAULT_ELECTRON_VERSION,
      icon: rawOptions.icon,
      name: typeof rawOptions.name === 'string' ? rawOptions.name : '',
-      out: rawOptions.out || process.cwd(),
+      out: rawOptions.out ?? process.cwd(),
      overwrite: rawOptions.overwrite,
      platform: rawOptions.platform,
-      portable: rawOptions.portable || false,
+      portable: rawOptions.portable ?? false,
      targetUrl:
        rawOptions.targetUrl === undefined
          ? '' // We'll plug this in later via upgrade
          : normalizeUrl(rawOptions.targetUrl),
      tmpdir: false, // workaround for electron-packager#375
      upgrade: rawOptions.upgrade !== undefined ? true : false,
-      upgradeFrom: rawOptions.upgrade,
-      win32metadata: rawOptions.win32metadata || {
+      upgradeFrom:
+        (rawOptions.upgradeFrom as string) ??
+        ((rawOptions.upgrade as string) || undefined),
+      win32metadata: rawOptions.win32metadata ?? {
        ProductName: rawOptions.name,
        InternalName: rawOptions.name,
        FileDescription: rawOptions.name,
@ -54,70 +63,70 @@ export async function getOptions(rawOptions: any): Promise<AppOptions> {
    },
    nativefier: {
      accessibilityPrompt: true,
-      alwaysOnTop: rawOptions.alwaysOnTop || false,
-      backgroundColor: rawOptions.backgroundColor || null,
-      basicAuthPassword: rawOptions.basicAuthPassword || null,
-      basicAuthUsername: rawOptions.basicAuthUsername || null,
-      blockExternalUrls: rawOptions.blockExternalUrls || false,
-      bookmarksMenu: rawOptions.bookmarksMenu || null,
-      bounce: rawOptions.bounce || false,
+      alwaysOnTop: rawOptions.alwaysOnTop ?? false,
+      backgroundColor: rawOptions.backgroundColor,
+      basicAuthPassword: rawOptions.basicAuthPassword,
+      basicAuthUsername: rawOptions.basicAuthUsername,
+      blockExternalUrls: rawOptions.blockExternalUrls ?? false,
+      bookmarksMenu: rawOptions.bookmarksMenu,
+      bounce: rawOptions.bounce ?? false,
      browserwindowOptions: rawOptions.browserwindowOptions,
-      clearCache: rawOptions.clearCache || false,
-      counter: rawOptions.counter || false,
+      clearCache: rawOptions.clearCache ?? false,
+      counter: rawOptions.counter ?? false,
      crashReporter: rawOptions.crashReporter,
-      disableContextMenu: rawOptions.disableContextMenu,
-      disableDevTools: rawOptions.disableDevTools,
-      disableGpu: rawOptions.disableGpu || false,
-      diskCacheSize: rawOptions.diskCacheSize || null,
+      disableContextMenu: rawOptions.disableContextMenu ?? false,
+      disableDevTools: rawOptions.disableDevTools ?? false,
+      disableGpu: rawOptions.disableGpu ?? false,
+      diskCacheSize: rawOptions.diskCacheSize,
      disableOldBuildWarning:
-        rawOptions.disableOldBuildWarningYesiknowitisinsecure || false,
-      enableEs3Apis: rawOptions.enableEs3Apis || false,
-      fastQuit: rawOptions.fastQuit || false,
+        rawOptions.disableOldBuildWarningYesiknowitisinsecure ?? false,
+      enableEs3Apis: rawOptions.enableEs3Apis ?? false,
+      fastQuit: rawOptions.fastQuit ?? false,
      fileDownloadOptions: rawOptions.fileDownloadOptions,
-      flashPluginDir: rawOptions.flashPath || rawOptions.flash || null,
-      fullScreen: rawOptions.fullScreen || false,
-      globalShortcuts: null,
-      hideWindowFrame: rawOptions.hideWindowFrame,
-      ignoreCertificate: rawOptions.ignoreCertificate || false,
-      ignoreGpuBlacklist: rawOptions.ignoreGpuBlacklist || false,
-      inject: rawOptions.inject || [],
-      insecure: rawOptions.insecure || false,
-      internalUrls: rawOptions.internalUrls || null,
-      lang: rawOptions.lang || undefined,
-      maximize: rawOptions.maximize || false,
+      flashPluginDir: rawOptions.flashPath,
+      fullScreen: rawOptions.fullScreen ?? false,
+      globalShortcuts: undefined,
+      hideWindowFrame: rawOptions.hideWindowFrame ?? false,
+      ignoreCertificate: rawOptions.ignoreCertificate ?? false,
+      ignoreGpuBlacklist: rawOptions.ignoreGpuBlacklist ?? false,
+      inject: rawOptions.inject ?? [],
+      insecure: rawOptions.insecure ?? false,
+      internalUrls: rawOptions.internalUrls,
+      lang: rawOptions.lang,
+      maximize: rawOptions.maximize ?? false,
      nativefierVersion: packageJson.version,
      processEnvs: rawOptions.processEnvs,
-      proxyRules: rawOptions.proxyRules || null,
-      showMenuBar: rawOptions.showMenuBar || false,
-      singleInstance: rawOptions.singleInstance || false,
-      titleBarStyle: rawOptions.titleBarStyle || null,
-      tray: rawOptions.tray || false,
+      proxyRules: rawOptions.proxyRules,
+      showMenuBar: rawOptions.showMenuBar ?? false,
+      singleInstance: rawOptions.singleInstance ?? false,
+      titleBarStyle: rawOptions.titleBarStyle,
+      tray: rawOptions.tray ?? false,
      userAgent: rawOptions.userAgent,
-      userAgentHonest: rawOptions.userAgentHonest || false,
-      verbose: rawOptions.verbose,
+      userAgentHonest: rawOptions.userAgentHonest ?? false,
+      verbose: rawOptions.verbose ?? false,
      versionString: rawOptions.versionString,
-      width: rawOptions.width || 1280,
-      height: rawOptions.height || 800,
+      width: rawOptions.width ?? 1280,
+      height: rawOptions.height ?? 800,
      minWidth: rawOptions.minWidth,
      minHeight: rawOptions.minHeight,
      maxWidth: rawOptions.maxWidth,
      maxHeight: rawOptions.maxHeight,
-      widevine: rawOptions.widevine || false,
+      widevine: rawOptions.widevine ?? false,
      x: rawOptions.x,
      y: rawOptions.y,
-      zoom: rawOptions.zoom || 1.0,
+      zoom: rawOptions.zoom ?? 1.0,
    },
  };

  if (options.nativefier.verbose) {
    log.setLevel('trace');
    try {
-      // eslint-disable-next-line @typescript-eslint/no-var-requires
-      require('debug').enable('electron-packager');
-    } catch (err) {
-      log.debug(
+      debug.enable('electron-packager');
+    } catch (err: unknown) {
+      log.error(
        'Failed to enable electron-packager debug output. This should not happen,',
        'and suggests their internals changed. Please report an issue.',
+        err,
      );
    }

@ -145,13 +154,17 @@ export async function getOptions(rawOptions: any): Promise<AppOptions> {
  }

  if (options.nativefier.widevine) {
-    const widevineElectronVersion = `${options.packager.electronVersion}-wvvmp`;
+    const widevineElectronVersion = `${
+      options.packager.electronVersion as string
+    }-wvvmp`;
    try {
      await axios.get(
        `https://github.com/castlabs/electron-releases/releases/tag/v${widevineElectronVersion}`,
      );
-    } catch (error) {
-      throw `\nERROR: castLabs Electron version "${widevineElectronVersion}" does not exist. \nVerify versions at https://github.com/castlabs/electron-releases/releases. \nAborting.`;
+    } catch {
+      throw new Error(
+        `\nERROR: castLabs Electron version "${widevineElectronVersion}" does not exist. \nVerify versions at https://github.com/castlabs/electron-releases/releases. \nAborting.`,
+      );
    }

    options.packager.electronVersion = widevineElectronVersion;
@ -173,7 +186,7 @@ export async function getOptions(rawOptions: any): Promise<AppOptions> {
  }

  if (options.nativefier.userAgentHonest && options.nativefier.userAgent) {
-    options.nativefier.userAgent = null;
+    options.nativefier.userAgent = undefined;
    log.warn(
      `\nATTENTION: user-agent AND user-agent-honest/honest were provided. In this case, honesty wins. user-agent will be ignored`,
    );
@ -181,11 +194,19 @@ export async function getOptions(rawOptions: any): Promise<AppOptions> {

  options.packager.platform = normalizePlatform(options.packager.platform);

-  if (options.nativefier.width > options.nativefier.maxWidth) {
+  if (
+    options.nativefier.maxWidth &&
+    options.nativefier.width &&
+    options.nativefier.width > options.nativefier.maxWidth
+  ) {
    options.nativefier.width = options.nativefier.maxWidth;
  }

-  if (options.nativefier.height > options.nativefier.maxHeight) {
+  if (
+    options.nativefier.maxHeight &&
+    options.nativefier.height &&
+    options.nativefier.height > options.nativefier.maxHeight
+  ) {
    options.nativefier.height = options.nativefier.maxHeight;
  }

@ -202,8 +223,8 @@ export async function getOptions(rawOptions: any): Promise<AppOptions> {

  if (rawOptions.globalShortcuts) {
    log.debug('Using global shortcuts file at', rawOptions.globalShortcuts);
-    const globalShortcuts = JSON.parse(
-      fs.readFileSync(rawOptions.globalShortcuts).toString(),
+    const globalShortcuts = parseJson<GlobalShortcut[]>(
+      fs.readFileSync(rawOptions.globalShortcuts as string).toString(),
    );
    options.nativefier.globalShortcuts = globalShortcuts;
  }
@ -213,7 +234,7 @@ export async function getOptions(rawOptions: any): Promise<AppOptions> {
  return options;
 }

-export function normalizePlatform(platform: string): string {
+export function normalizePlatform(platform: string | undefined): string {
  if (!platform) {
    return inferPlatform();
  }
--- a/src/utils/parseUtils.test.ts
+++ b/src/utils/parseUtils.test.ts
@ -14,8 +14,12 @@ test.each([
  [undefined, true, true],
  [undefined, false, false],
 ])(
-  'parseBoolean("%s") === %s',
-  (testString: string, expectedResult: boolean, _default: boolean) => {
-    expect(parseBoolean(testString, _default)).toBe(expectedResult);
+  'parseBoolean("%s") === %s (default = %s)',
+  (
+    testValue: boolean | string | number | undefined,
+    expectedResult: boolean,
+    _default: boolean,
+  ) => {
+    expect(parseBoolean(testValue, _default)).toBe(expectedResult);
  },
 );
--- a/src/utils/parseUtils.ts
+++ b/src/utils/parseUtils.ts
@ -3,9 +3,12 @@ import * as log from 'loglevel';
 import { isWindows } from '../helpers/helpers';

 export function parseBoolean(
-  val: boolean | string | number,
+  val: boolean | string | number | undefined,
  _default: boolean,
 ): boolean {
+  if (val === undefined) {
+    return _default;
+  }
  try {
    if (typeof val === 'boolean') {
      return val;
@ -23,7 +26,7 @@ export function parseBoolean(
      default:
        return _default;
    }
-  } catch (_) {
+  } catch {
    return _default;
  }
 }
@ -39,11 +42,11 @@ export function parseBooleanOrString(val: string): boolean | string {
  }
 }

-export function parseJson(val: string): any {
-  if (!val) return {};
+export function parseJson<Type>(val: string): Type | undefined {
+  if (!val) return undefined;
  try {
-    return JSON.parse(val);
-  } catch (err) {
+    return JSON.parse(val) as Type;
+  } catch (err: unknown) {
    const windowsShellHint = isWindows()
      ? `\n   In particular, Windows cmd doesn't have single quotes, so you have to use only double-quotes plus escaping: "{\\"someKey\\": \\"someValue\\"}"`
      : '';
--- a/src/utils/sanitizeFilename.ts
+++ b/src/utils/sanitizeFilename.ts
@ -4,7 +4,7 @@ import sanitize = require('sanitize-filename');
 import { DEFAULT_APP_NAME } from '../constants';

 export function sanitizeFilename(
-  platform: string,
+  platform: string | undefined,
  filenameToSanitize: string,
 ): string {
  let result: string = sanitize(filenameToSanitize);
--- a/tsconfig.json
+++ b/tsconfig.json
@ -1,32 +1,36 @@
 {
  "compilerOptions": {
-      "allowJs": false,
-      "declaration": true,
-      "incremental": true,
-      "module": "commonjs",
-      "moduleResolution": "node",
-      "outDir": "./lib",
-      "resolveJsonModule": true,
-      "skipLibCheck": true,
-      "sourceMap": true,
-      // Bumping the minimum required Node version? You must bump:
-      //   1. package.json -> engines.node
-      //   2. package.json -> devDependencies.@types/node
-      //   3. tsconfig.json -> {target, lib}
-      //   4. .github/workflows/ci.yml -> node-version
-      //
-      // Here in tsconfig.json, we want to set the `target` and `lib` keys
-      // to the "best" values for the minimum/required version of node.
-      // TS doesn't offer any easy "preset" for this, so the best we have is to
-      // believe people who know which {syntax, library} parts of current EcmaScript
-      // are supported for our version of Node, and use what they recommend.
-      // For the current Node version, I followed
-      // https://stackoverflow.com/questions/59787574/typescript-tsconfig-settings-for-node-js-12
-      "target": "es2019",
-      // In `lib` we add `dom`, to tell tsc it's okay to use the URL object (which is in Node >= 7)
-      "lib": ["es2020", "dom"]
+    "allowJs": false,
+    "declaration": true,
+    "incremental": true,
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "outDir": "./lib",
+    "resolveJsonModule": true,
+    "skipLibCheck": true,
+    "sourceMap": true,
+    "strict": true,
+    // Bumping the minimum required Node version? You must bump:
+    //   1. package.json -> engines.node
+    //   2. package.json -> devDependencies.@types/node
+    //   3. tsconfig.json -> {target, lib}
+    //   4. .github/workflows/ci.yml -> node-version
+    //
+    // Here in tsconfig.json, we want to set the `target` and `lib` keys
+    // to the "best" values for the minimum/required version of node.
+    // TS doesn't offer any easy "preset" for this, so the best we have is to
+    // believe people who know which {syntax, library} parts of current EcmaScript
+    // are supported for our version of Node, and use what they recommend.
+    // For the current Node version, I followed
+    // https://stackoverflow.com/questions/59787574/typescript-tsconfig-settings-for-node-js-12
+    "target": "es2019",
+    // In `lib` we add `dom`, to tell tsc it's okay to use the URL object (which is in Node >= 7)
+    "lib": [
+      "es2020",
+      "dom"
+    ]
  },
  "include": [
-      "./src/**/*"
+    "./src/**/*"
  ]
 }