fixes

BlacksmithWorkshop/BlacksmithWorkshopBusinessLogic/BusinessLogics/ShopLogic.cs

@@ -111,7 +111,7 @@ namespace BlacksmithWorkshopBusinessLogic.BusinessLogics
 			{
 				throw new ArgumentNullException(nameof(model));
 			}
-			if (count <= 0)
+			if (count < 0)
 			{
 				throw new ArgumentException("Количество изделий должно быть больше 0", nameof(count));
 			}