fix.修复aria2下载完成后的处理错误

https://github.com/MaaAssistantArknights/MaaAssistantArknights/issues/322

src/MeoAsstGui/ViewModels/VersionUpdateViewModel.cs

@@ -472,7 +472,6 @@ namespace MeoAsstGui
             }
         }
 
-
         private bool DownloadFileForAria2(string url, string filePath, string fileName)
         {
             var aria2FilePath = Path.GetFullPath(Directory.GetCurrentDirectory() + "/aria2c.exe");
@@ -500,11 +499,11 @@ namespace MeoAsstGui
 
             aria2Process.Start();
             aria2Process.WaitForExit();
+            var exit_code = aria2Process.ExitCode;
             aria2Process.Close();
-            return aria2Process.ExitCode == 0;
+            return exit_code == 0;
         }
 
-
         private bool DownloadFileForCSharpNative(string url, string filePath, string contentType = null)
         {
             // 创建 Http 请求