Patch for Shopware Plug-In

We have an existing Plug-In for Shopware 5 shop system. This plug-in provides an integration for our web analytics tracking. Goal of this project is to develop a patch that fixes the following bug: Environment: - Shopware, Version 5 (latest version). - with econda tracking plug-in installed and enabled (see links below) Steps to reproduce: 1. Set the following configuration option: - Backend UI > Configuration > Frontend > Shopping cart / item details > Do not show on sale products that are out of stock => Setting: "Yes" 2. Prepare "on sale" article - Backend UI > Items > edit any item and set the following settings: - - Basic info > Settings > On sale => checked - - Basic info > Settings > Stock => 1 3. Go to shop frontend and... - Navigate to prepared article - add this article to cart - buy cart (complete checkout) => at the end of checkout, a PHP error will raise PHP Error (at end of checkout): Fatal error: Call to a member function getVariantId() on null in /BASE_PATH/engine/Shopware/Bundle/StoreFrontBundle/Gateway/DBAL/[login to view URL] on line 94 Reason seems to be: * Our plug-in > method onActionPostDispatchFrontendCheckout calls getProductConfig (Service shopware_storefront.product_service) * shopware_storefront.product_service checks if article is available and due to the "do not show on sale products that are out of stock" and the fact, that our test article has now 0 item in stock (was 1, we bought the last, so now it's zero), service returns null. * Now the line $configservice->getProductConfiguration() uses null instead of an article record and fails. Fix: * There must be no fatal error * We still need the article data for web tracking (so just checking for null will not work) Additional information: * econda tracking plug-in: [login to view URL] * git repository for plug-in: [login to view URL] (you'll need to register first) * Stack trace as attachment Plugin features: The econda tracking plug-in renders information about the current view as JavaScript code on all shop frontend pages. Our (separate) JavaScript library (often called "[login to view URL]") will send tracking requests based on this data to our SaaS tracking server. * Tracking documentation: https://support.econda.de/display/INEN/Tracking+Code