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