fixed an empty notification about closing files

app/scripts/models/app-model.js

@@ -233,6 +233,9 @@ class AppModel {
     }
 
     closeAllFiles() {
+        if (!this.files.hasOpenFiles()) {
+            return;
+        }
         for (const file of this.files) {
             file.close();
             this.fileClosed(file);

app/scripts/views/app-view.js

@@ -615,6 +615,9 @@ class AppView extends View {
     }
 
     closeAllFilesAndShowFirst() {
+        if (!this.model.files.hasOpenFiles()) {
+            return;
+        }
         let fileToShow = this.model.files.find(
             (file) => !file.demo && !file.created && !file.skipOpenList
         );