diff -u b/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js b/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js
--- b/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js
+++ b/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js
@@ -11,6 +11,8 @@
    * Provides the summary for the "drupalimage" plugin settings vertical tab.
    *
    * @type {Drupal~behavior}
+   *
+   * @prop {Drupal~behaviorAttach} attach
    *   Attaches summary behaviour to the "drupalimage" settings vertical tab.
    */
   Drupal.behaviors.ckeditorDrupalImageSettingsSummary = {