Issue #3238915: Refactor (if feasible) uses of the jQuery ready function to use VanillaJS

core/modules/ckeditor5/src/Plugin/CKEditor4To5Upgrade/Core.php

@@ -216,7 +216,7 @@ public function computeCKEditor5PluginSubsetConfiguration(string $cke5_plugin_id
         }
         // Otherwise, only enable headings that allowed by the restrictions.
         $configuration = [];
-        foreach (range(2, 6) as $index) {
+        foreach (range(1, 6) as $index) {
           // Merely checking the existence of the array key is sufficient; this
           // plugin does not set or need any additional attributes.
           // @see \Drupal\filter\Plugin\FilterInterface::getHTMLRestrictions()