Fatal error: Uncaught Error: Class "OCA\WorkflowEngine\Check\AbstractStringCheck" not found in /var/www/html/nextcloud/apps/workflowengine/lib/Check/FileMimeType.php:16 Stack trace: #0 {main} thrown in /var/www/html/nextcloud/apps/workflowengine/lib/Check/FileMimeType.php on line 16