Fatal error: Uncaught Error: Class 'Drupal\Component\Plugin\Derivative\DeriverBase' not found in /var/www/html/tmp/contrib/flag/src/Plugin/Derivative/EntityFlagTypeDeriver.php:11 Stack trace: #0 {main} thrown in /var/www/html/tmp/contrib/flag/src/Plugin/Derivative/EntityFlagTypeDeriver.php on line 11