System.NullReferenceException: Object reference not set to an instance of an object.
at Dynamicweb.eCommerce.Products.Group.get_AllGroupsByLanguageID(String languageID)
at Dynamicweb.eCommerce.Products.Group.get_GroupByID(String groupID, String languageId, String defaultLanguageId)
at Dynamicweb.eCommerce.Products.Categories.CategoryCollection._Closure$__2-0._Lambda$__1(String key)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at Dynamicweb.eCommerce.Products.Categories.CategoryCollection._Closure$__2-0._Lambda$__2(String groupId)
at Dynamicweb.eCommerce.Products.Categories.CategoryCollection._Closure$__3-0._Lambda$__0(IEnumerable`1 col, Int32 level)
at Dynamicweb.eCommerce.Products.Categories.CategoryCollection.GetCategories(IEnumerable`1 groupsIds, Func`2 getCategoryFn, Func`2 getGroupRelationsByChildId, Func`3 createCategoryGroup, Int32 minLevel, Nullable`1 maxLevel)
at Dynamicweb.eCommerce.Products.Categories.CategoryCollection.GetCategories(IEnumerable`1 groups, Int32 minLevel, Nullable`1 maxLevel, String languageId, String defaultLangId)
at Dynamicweb.eCommerce.Products.Product.GetCategories()
at Dynamicweb.eCommerce.Frontend.Renderer.RenderProductCategories(Product product, Template template, String loopName)
at Dynamicweb.eCommerce.Frontend.Renderer.RenderProduct(Product Product, Boolean ExtendedProperties, Template Template, Int32 loopCounter, Boolean renderRelated, String productURL, Int32 quantity, Int32 wishListID, Boolean renderPublicList, Int32 orderLineOfProductCount)
at Dynamicweb.eCommerce.Frontend.Renderer.RenderProducts(ProductCollection Products, Template ParentTemplate, String LoopName, Int32 LoopCounter, Boolean renderRelatedProducts, Boolean renderRelatedLists)
at Dynamicweb.eCommerce.Frontend.Renderer.RenderProducts(ProductCollection Products, Template ParentTemplate)
at Dynamicweb.eCommerce.Frontend.Renderer.internalRenderProducts(ProductCollection products, Boolean isProductsFromIndex)
at Dynamicweb.eCommerce.Frontend.Frontend.ListProducts(ProductCollection products, String groupsIdent, Boolean hasBeenSorted)
at Dynamicweb.eCommerce.Frontend.Frontend.GetProductsFromIndexQuery()