Issue#3511945: Fix Not in menu error.

Closes #3511945

src/Plugin/Field/FieldWidget/MenuLinkWidget.php

@@ -102,8 +102,6 @@ class MenuLinkWidget extends WidgetBase {
     $entity = $items->getParent()->getValue();
     $element['#pre_render'][] = [MenuDetails::class, 'preRender'];
 
-    $element['#attached']['library'][] = 'menu_link/menu_link.form';
-
     $element['title'] = [
       '#type' => 'textfield',
       '#title' => $this->t('Menu link title'),
@@ -137,7 +135,7 @@ class MenuLinkWidget extends WidgetBase {
       '#group' => $entity->getEntityTypeId() === 'node' ? 'advanced' : NULL,
       '#attributes' => ['class' => ['menu-link-form']],
       '#attached' => [
-        'library' => ['menu_ui/drupal.menu_ui'],
+        'library' => ['menu_link/menu_link.form'],
       ],
     ];