Fatal error: Uncaught Error: Interface 'Drupal\Core\Mail\MailInterface' not found in /var/www/html/tmp/contrib/mailsystem/tests/modules/mailsystem_test/src/Plugin/Mail/DummySender.php:16 Stack trace: #0 {main} thrown in /var/www/html/tmp/contrib/mailsystem/tests/modules/mailsystem_test/src/Plugin/Mail/DummySender.php on line 16