diff --git a/core/modules/quickedit/js/quickedit.es6.js b/core/modules/quickedit/js/quickedit.es6.js
index 84fee16cdf..be39a966fc 100644
--- a/core/modules/quickedit/js/quickedit.es6.js
+++ b/core/modules/quickedit/js/quickedit.es6.js
@@ -512,6 +512,9 @@
 
     // @see https://www.drupal.org/node/2029999.
     // Create a Drupal.Ajax instance to load the form.
+    if (!drupalSettings.ajaxPageState.libraries.match('ckeditor/drupal.ckeditor').length) {
+      throw 'BUG';
+    }
     const loadEditorsAjax = Drupal.ajax({
       url: Drupal.url('quickedit/attachments'),
       submit: { 'editors[]': missingEditors },
diff --git a/core/modules/quickedit/js/quickedit.js b/core/modules/quickedit/js/quickedit.js
index 5c2cd95af0..892249a166 100644
--- a/core/modules/quickedit/js/quickedit.js
+++ b/core/modules/quickedit/js/quickedit.js
@@ -258,6 +258,9 @@
       return;
     }
 
+    if (!drupalSettings.ajaxPageState.libraries.match('ckeditor/drupal.ckeditor').length) {
+      throw 'BUG';
+    }
     var loadEditorsAjax = Drupal.ajax({
       url: Drupal.url('quickedit/attachments'),
       submit: { 'editors[]': missingEditors }