diff --git a/core/modules/ckeditor5/js/ckeditor5.js b/core/modules/ckeditor5/js/ckeditor5.js
index 4d6f4d18551..bd5f3facdf9 100644
--- a/core/modules/ckeditor5/js/ckeditor5.js
+++ b/core/modules/ckeditor5/js/ckeditor5.js
@@ -116,6 +116,10 @@
       });
     }
 
+    if (config === null) {
+      return null;
+    }
+
     return Object.entries(config).reduce((processed, [key, value]) => {
       if (typeof value === 'object') {
         // Check for null values.