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ComputersShop/ComputersShopBusinessLogic/BusinessLogics/ShopLogic.cs

@@ -32,6 +32,7 @@ namespace ComputersShopBusinessLogic.BusinessLogics
 
 			if (quantity <= 0)
 			{
+                return false;
                 throw new ArgumentException("Количество добавляемого изделия должно быть больше 0", nameof(quantity));
 			}
 

ComputersShop/ComputersShopFileImplement/Models/Shop.cs

@@ -99,8 +99,8 @@ namespace ComputersShopFileImplement.Models
             new XElement("ShopAddress", ShopAddress),
             new XElement("DateOpening", DateOpening.ToString()),
             new XElement("Capacity", Capacity.ToString()),
-            new XElement("Сomputers", ComputersCount.Select(x =>
-            new XElement("Сomputer",
+            new XElement("Computers", ComputersCount.Select(x =>
+            new XElement("Computer",
                 new XElement("Key", x.Key),
                 new XElement("Value", x.Value)))
                 .ToArray()));