Fatal error: Uncaught Error: Interface "Dhii\Collection\MutableContainerInterface" not found in /var/www/html1/wp-content/plugins/zettle-pos-integration/vendor/dhii/containers/src/FlashContainer.php:23 Stack trace: #0 {main} thrown in /var/www/html1/wp-content/plugins/zettle-pos-integration/vendor/dhii/containers/src/FlashContainer.php on line 23