Fatal error: Uncaught Error: Class "Drupal\image\Form\ImageEffectFormBase" not found in /home/www/drupal8/test/core/modules/image/src/Form/ImageEffectAddForm.php:15 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/image/src/Form/ImageEffectAddForm.php on line 15