Occur: Fix loading

occur-mode is part of replace which is only provided in emacs26+ and
builtin otherwise.

evil-collection.el

@@ -96,6 +96,15 @@ instance:
     (require 'evil-calendar)
     (evil-calendar-setup))"
   (interactive)
+  ;; We need to special case `occur' since it exists in `replace'.
+  (when (memq 'occur evil-collection-mode-list)
+    (if (<= emacs-major-version 25)
+        (progn
+          (require 'evil-occur)
+          (evil-occur-setup))
+      (with-eval-after-load 'replace
+        (require 'evil-occur)
+        (evil-occur-setup))))
   (dolist (mode evil-collection-mode-list)
     (let ((m mode)
           (reqs (list mode)))