nav-flash: fix syl20bnr#15617

based on doomemacs/doomemacs@ff58823

layers/+misc/nav-flash/funcs.el

@@ -21,13 +21,14 @@
 ;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 (defun nav-flash//blink-cursor (&rest _)
-  "Blink the line containing hte point.
+  "Blink the line containing the point.
 This makes it clear where the cursor has landed (typically after a large motion,
 like switching windows or 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)))))
 
 (defun nav-flash/blink-cursor-maybe (&rest _)
   "Like `nav-flash//blink-cursor', but no-ops if any following condition is met.