simplify OnStartup method

BetterGenshinImpact/App.xaml

@@ -1,9 +1,7 @@
 <Application x:Class="BetterGenshinImpact.App"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-             xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             Exit="OnExit"
-             Startup="OnStartup">
+             xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml">
     <Application.Resources>
         <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>

BetterGenshinImpact/App.xaml.cs

@@ -112,16 +112,14 @@ public partial class App : Application
     /// <summary>
     /// Occurs when the application is loading.
     /// </summary>
-    private void OnStartup(object sender, StartupEventArgs e)
+    protected override async void OnStartup(StartupEventArgs e)
     {
-        StartUp();
-    }
+        base.OnStartup(e);
 
-    private async void StartUp()
-    {
         try
         {
-            await StartUpCoreAsync();
+            RegisterEvents();
+            await _host.StartAsync();
             await UrlProtocolHelper.RegisterAsync();
         }
         catch (Exception ex)
@@ -136,19 +134,14 @@ public partial class App : Application
         }
     }
 
-    private async Task StartUpCoreAsync()
-    {
-        RegisterEvents();
-        await _host.StartAsync();
-    }
-
     /// <summary>
     /// Occurs when the application is closing.
     /// </summary>
-    private async void OnExit(object sender, ExitEventArgs e)
+    protected override async void OnExit(ExitEventArgs e)
     {
-        await _host.StopAsync();
+        base.OnExit(e);
 
+        await _host.StopAsync();
         _host.Dispose();
     }