An error occurred while attaching module (Dynamicweb.Frontend.Content)

System.NullReferenceException: Object reference not set to an instance of an object.
   at DwCustomModules.CustomModules.ProductFilter.Frontend.GetTemplateTags(Group selectedGroup, Template template) in C:\Repositories\Medilink\SaltsMedilinkRedux\Application (9.19.3)\CustomModules\ProductFilter\ProductFilter.cs:line 182
   at DwCustomModules.CustomModules.ProductFilter.Frontend.GetContent() in C:\Repositories\Medilink\SaltsMedilinkRedux\Application (9.19.3)\CustomModules\ProductFilter\ProductFilter.cs:line 47
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)