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

System.ArgumentNullException: Value cannot be null.
Parameter name: value
   at Dynamicweb.Core.Ensure.That[TException](Boolean condition, String message)
   at Dynamicweb.Ecommerce.Common.Context.SetCurrency(Currency value)
   at Custom.Lopolight.Core.Notifications.LiveIntegration.ProductInfoBeforeGenerateXmlSubscriber.OnNotify(String notification, NotificationArgs args)
   at Dynamicweb.Extensibility.Notifications.NotificationManager.Notify(String notification, NotificationArgs eventArgs)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.XmlGenerators.ProductInfoXmlGenerator.GenerateProductInfoXml(Settings currentSettings, List`1 products, ProductInfoXmlGeneratorSettings settings, Logger logger)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.ProductManager.BuildProductRequest(Settings settings, List`1 products, LiveContext context, Logger logger)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.ProductManager.FetchProductInfosInternal(List`1 productsForRequest, ResponseCacheLevel productCacheLevel, LiveContext context, Settings settings, Logger logger, Boolean updateCache)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.ProductManager.FetchProductInfos(List`1 products, LiveContext context, Settings settings, Logger logger, Boolean doCurrencyCheck, Boolean updateCache)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.StockProvider.FindStockLevel(Product product)
   at Dynamicweb.Ecommerce.Stocks.StockLevelManager.FindStockLevel(Product product, String unitId, StockLocation stockLocation)
   at Dynamicweb.Ecommerce.Products.Product.GetUnitStock(StockLocation stockLocation, String unitId)
   at Dynamicweb.Ecommerce.Frontend.Renderer.RenderProduct(Product product, Boolean extendedProperties, Template template, Int32 loopCounter, Boolean renderRelated, String productUrl, Int32 quantity, Int32 wishListId, Boolean renderPublicList, Boolean isRecursiveCall, Lazy`1 categoryFieldSorting, Int32 orderLineOfProductCount, RenderingContext renderingContext, String unitId)
   at Dynamicweb.Ecommerce.Frontend.Renderer.RenderProduct(Product product, Boolean extendedProperties, String unitId)
   at Dynamicweb.Ecommerce.Frontend.Frontend.EcomRender()
   at Dynamicweb.Ecommerce.Frontend.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)