Fatal error: Uncaught Error: Class "Drupal\webform\Plugin\WebformHandlerBase" not found in /home/www/drupal8/test/modules/webform/src/Plugin/WebformHandler/DebugWebformHandler.php:24 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/webform/src/Plugin/WebformHandler/DebugWebformHandler.php on line 24