Fatal error: Uncaught Error: Class "Drupal\ckeditor\CKEditorPluginBase" not found in /home/www/drupal8/test/core/modules/ckeditor/src/Plugin/CKEditorPlugin/Language.php:21 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/ckeditor/src/Plugin/CKEditorPlugin/Language.php on line 21