Fix 'wrong type arg: overlayp' error from ivy+nav-flash (#4749)

* Fix for missing overlay

Overlay might be nil before being used, so replicate what the package does

* Neater for for nav-flash issue

* Properly check for the value

Author: elken

modules/ui/nav-flash/autoload.el

@@ -10,7 +10,8 @@ jumping to another part of the file)."
   (unless (minibufferp)
     (nav-flash-show)
     ;; only show in the current window
-    (overlay-put compilation-highlight-overlay 'window (selected-window))))
+    (when (overlayp compilation-highlight-overlay)
+      (overlay-put compilation-highlight-overlay 'window (selected-window)))))
 
 ;;;###autoload
 (defun +nav-flash-blink-cursor-maybe (&rest _)