Debug & Fix Third Party Magento Module that is causing Linnworks API Inventory Sync to Fail

Hello, I have recently installed a Third Party extension into Magento that unfortunately is causing the SOAP API in Linnworks Order Management software to fail when the magento inventory level requires updating. All other Linnworks API's are running as they should, it is only the inventory sync api call that is failing. The fault that is being returned is.... Failed to update inventory for one or more skus with top error: Call to a member function getId() on null. I cannot change the API call Linnworks makes in any way, it is controlled by Linnworks Company themselves. I require a fix on the newly installed Module/extension that is causing the issue when it is enabled. The fix must not affect the current website or the operation of this new module in any way. I require someone who understands and has experience in Linnworks so i do not need to explain the simple details. The module that is causing the issue is an update to the website so customers can personalise their own product with text. After the fix I require the function of the module to remain exactly the same as it today Here is a link on a Forum that explains in more detail the error i am getting [login to view URL]