Check for window before window.QUnit (#25199)

diff --git a/js/src/util.js b/js/src/util.js
index 14653c86e082f0c464db5801fd502376fe44e236..0ffbb76a3e5205e1184b73d407bff12138e7ac0f 100644 (file)
--- a/js/src/util.js
+++ b/js/src/util.js
@@ -39,7 +39,7 @@ const Util = (($) => {
   }
 
   function transitionEndTest() {
-    if (window.QUnit) {
+    if (typeof window !== 'undefined' && window.QUnit) {
       return false
     }