What can cause the following error log when retrieving stock information from the Commerce Engine?
00186 04:18:52 ERROR ClientCertificateValidationMiddleware: Message = Object reference not set to an instance of an object. System.NullReferenceException: Object reference not set to an instance of an object. at Sitecore.Commerce.Plugin.Inventory.ApiController.<GetBulkStockInformation>d__1.MoveNext()
Is it related to client certificate or can it be any error during processing of the GetBulkStockInformation?