SushiBar/SushiBarFileImplement/Implements/OrderStorage.cs

@@ -70,7 +70,7 @@ namespace SushiBarFileImplement.Implements
             }
             return null;
         }
-        private OrderViewModel AttachSushiName(OrderViewModel model)
+        private OrderViewModel AttachSushiName(OrderViewModel ?model)
         {
             if (model == null) { return null; }
             model.SushiName = source.Sushis.First(x => x.Id == model.SushiId).SushiName;