Fatal error: Uncaught Error: Interface "Inpsyde\Zettle\Webhooks\Handler\WebhookHandler" not found in /var/www/html1/wp-content/plugins/zettle-pos-integration/modules/zettle-webhooks/src/Handler/InventoryTrackingStoppedHandler.php:9 Stack trace: #0 {main} thrown in /var/www/html1/wp-content/plugins/zettle-pos-integration/modules/zettle-webhooks/src/Handler/InventoryTrackingStoppedHandler.php on line 9