SelfPropelledArtilleryUnit/SelfPropelledArtilleryUnit/FormSPAUCollection.cs

@@ -63,8 +63,16 @@ namespace SelfPropelledArtilleryUnit
             {
                 return;
             }
-            int pos = Convert.ToInt32(maskedTextBoxNumber.Text);
-            if (_SPAUs - pos != null)
+            int pos;
+            try {
+                
+                pos = Convert.ToInt32(maskedTextBoxNumber.Text); 
+            }
+            catch {
+                MessageBox.Show("Не удалось удалить объект");
+                return;
+            }
+            if (_SPAUs - pos)
             {
                 MessageBox.Show("Объект удален");
                 pictureBoxCollection.Image = _SPAUs.ShowSPAUs();

SelfPropelledArtilleryUnit/SelfPropelledArtilleryUnit/SPAUGenericCollection.cs

@@ -71,14 +71,18 @@ namespace SelfPropelledArtilleryUnit.Generics
         /// <param name="collect"></param>
         /// <param name="pos"></param>
         /// <returns></returns>
-        public static T? operator -(SPAUGenericCollection<T, U> collect, int pos)
+        public static bool operator -(SPAUGenericCollection<T, U> collect, int pos)
         {
             T? obj = collect._collection.Get(pos);
             if (obj != null)
             {
                 collect._collection.Remove(pos);
             }
-            return obj;
+            else
+            {
+                return false;
+            }
+            return true;
         }
         /// <summary>
         /// Получение объекта IMoveableObject