Issue #3367651 by Ahmad Smhan, MakerTimSWIS: Attached Library set to string instead of array

(cherry picked from commit 36414458)

core/lib/Drupal/Core/Entity/EntityForm.php

@@ -255,7 +255,7 @@ protected function actions(array $form, FormStateInterface $form_state) {
         ],
         '#url' => $route_info,
         '#attached' => [
-          'library' => 'core/drupal.dialog.ajax',
+          'library' => ['core/drupal.dialog.ajax'],
         ],
       ];
     }