Update src/c#/GeneralUpdate.Core/GeneralUpdateBootstrap.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: JusterZhu

src/c#/GeneralUpdate.Core/GeneralUpdateBootstrap.cs

@@ -282,6 +282,7 @@ protected override GeneralUpdateBootstrap StrategyFactory()
         private GeneralUpdateBootstrap AddListener<TArgs>(Action<object, TArgs> action)
             where TArgs : EventArgs
         {
+            if (action is null) throw new ArgumentNullException(nameof(action));
             EventManager.Instance.AddListener(action);
             return this;
         }