Task done

Repository/JsonRepository.cs

@@ -32,24 +32,28 @@ public class JsonRepository : IRepository
         return null;
     }
 
-    public void Write(User item)
+    public int Write(User item)
     {
         try
         {
             string json = JsonSerializer.Serialize(item);
             File.WriteAllText(_fileName, json);
+            return 0;
         }
         catch (JsonException e)
         {
             WriteToStdErr($"JSON error: {e.Message}");
+            return e.GetHashCode();
         }
         catch (IOException e)
         {
             WriteToStdErr($"File I/O error: {e.Message}");
+            return e.GetHashCode();
         }
         catch (Exception e)
         {
             WriteToStdErr($"Unexpected error: {e.Message}");
+            return e.GetHashCode();
         }
     }