应用程序在从Google获取用户配置文件时停止响应

我尝试使用google.net api获取经过验证的用户电子邮件,但应用程序在我标记为****的行中停止响应。当我第一次运行它时,它打开浏览器并请求我的Gmail,在选择Gmail之后,它说现在你可以关闭浏览器窗口,但是我的桌面应用程序将停止响应。下次我运行应用程序时,它会停止响应,除非我删除 Google.Apis.Auth 文件夹从 AppData\Roaming :

        private async Task VerifyEmail()
        {
            UserCredential credential;
            credential = await GoogleWebAuthorizationBroker.AuthorizeAsync(
                new ClientSecrets
                {
                    ClientId = "xxxx.apps.googleusercontent.com",
                    ClientSecret = "xxxx-xxxxx"
                },
                new[] { Google.Apis.Oauth2.v2.Oauth2Service.Scope.UserinfoEmail },
                "user",
                CancellationToken.None,
                new FileDataStore("My.DataStore")
                );

            var initializer =
        new BaseClientService.Initializer()
        {
            HttpClientInitializer = credential,
            ApplicationName = "My App",
        };
            var oauthSerivce = new Google.Apis.Oauth2.v2.Oauth2Service(initializer);

            // app stops responding here **** :
            var userInfo = await oauthSerivce.Userinfo.Get().ExecuteAsync();
            MessageBox.Show(userInfo.Email);
        }