[Bug] How do i get what is causing this specific error ?

[davidbuckleyni]

I am getting the following error in my application it seems to be around when am using the messaing centre but its giving me no real detail as to what the issue actually is as most of the references it pointing to is xamrain forms under the hood code.

It looks like its something to do with this call.

   ```
  public async void CopyTOWeightLfitingScreen()
    {

        var player = await api.GetPlayerById(PlayerId);
        var session = api.GetSessionById(SessionId);
        if (player != null)
        {
            WeightLifting weightLiftingRecord = new WeightLifting();
            weightLiftingRecord.SessionId = SessionId;
            weightLiftingRecord.SessionStartDate = session.StartDate;
            weightLiftingRecord.SessionEndDate = session.EndDate;
            weightLiftingRecord.PlayersId = player.Id;
            weightLiftingRecord.PU = player.DefaultPU;
            weightLiftingRecord.PUReps = (int?)player.DefaultPUReps;
            weightLiftingRecord.OP = player.DefaultOP;
            weightLiftingRecord.OPReps = (int?)player.DefaultOPReps;
            weightLiftingRecord.BikeCalories = player.DefaultBikeCalories;
            weightLiftingRecord.BikeSeconds = player.DefaultBikeSeconds;
            weightLiftingRecord.BP = player.DefaultBP;
            weightLiftingRecord.BPReps = (int?)player.DefaultBPReps;
            weightLiftingRecord.BroadJumpFeet = player.DefaultBroadJumpFeet;
            weightLiftingRecord.BroadJumpInches = player.DefaultBroadJumpInches;
            weightLiftingRecord.APU = player.DefaultAdvancedPu;
            weightLiftingRecord.APUReps = (int?)player.DefaultAdvancedPuReps;
            weightLiftingRecord.OneFityYards = player.DefaultOneFityYards;
            weightLiftingRecord.TwentyFiveYards = player.DefaultTwentyFiveYards;
            weightLiftingRecord.IsActive = player.IsActive;
            weightLiftingRecord.IsDeleted = player.IsDeleted;
            weightLiftingRecord.CreatedBy = db.GetActiveUser();
            weightLiftingRecord.isWorkOutHistory = false;
            await api.AddAWeightLifting(weightLiftingRecord);
            await DisplayAlert(Constants.AppName, "Player added automatically to weight screen", null, "OK");

        }

But I cant figure out what it is causing it.

This is the code that is calling the above.

    private async void btnAddPlayerToSession_Clicked(object sender, EventArgs e)
    {
        //var session = dgSessions.SelectedItem as Session;
        //if (session != null)
        //{
        //    var viewForm = new AddAPlayerToSession(session.Id);
        //    await Navigation.PushAsync(viewForm);
        //}

        var session = dgSessions.SelectedItem as Session;
        string playersSelected = string.Empty;
        if (session != null)
        {
            SessionId = session.Id;
               var page = new PlayerSelection(session.Id,true,"");

            MessagingCenter.Subscribe<App, string>(App.Current, "PlayersSelected", (snd, arg) =>
            {
                playersSelected = arg.ToString();
                Int32.TryParse(arg.ToString(), out int PlayerIdresult);
                PlayerId = PlayerIdresult;
                Task.Run(async () =>
                {
                    CopyTOWeightLfitingScreen();


                });

            });
            await PopupNavigation.Instance.PushAsync(page);

             BindGrid();

        }
    }

at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00081] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/corlib/System.Reflection/RuntimeMethodInfo.cs:409
at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/external/corefx/src/Common/src/CoreLib/System/Reflection/MethodBase.cs:53
at Xamarin.Forms.MessagingCenter+Subscription.InvokeCallback (System.Object sender, System.Object args) [0x00064] in D:\a\1\s\Xamarin.Forms.Core\MessagingCenter.cs:94
at Xamarin.Forms.MessagingCenter.InnerSend (System.String message, System.Type senderType, System.Type argType, System.Object sender, System.Object args) [0x0006b] in D:\a\1\s\Xamarin.Forms.Core\MessagingCenter.cs:217
at Xamarin.Forms.MessagingCenter.Xamarin.Forms.IMessagingCenter.Send[TSender,TArgs] (TSender sender, System.String message, TArgs args) [0x00013] in D:\a\1\s\Xamarin.Forms.Core\MessagingCenter.cs:115
at Xamarin.Forms.MessagingCenter.Send[TSender,TArgs] (TSender sender, System.String message, TArgs args) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\MessagingCenter.cs:108
at Xamarin.Forms.Page.DisplayAlert (System.String title, System.String message, System.String accept, System.String cancel, Xamarin.Forms.FlowDirection flowDirection) [0x00046] in D:\a\1\s\Xamarin.Forms.Core\Page.cs:223
at Xamarin.Forms.Page.DisplayAlert (System.String title, System.String message, System.String accept, System.String cancel) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Page.cs:206
at THEHOCKEYLAB.Views.SessionPage.CopyTOWeightLfitingScreen () [0x0042c] in D:\GitMaster\thehockeylabl.mobile\THEHOCKEYLAB\THEHOCKEYLAB\Views\SessionPage.xaml.cs:175
at System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.b__7_1 (System.Object state) [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/AsyncMethodBuilder.cs:1037
at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context (System.Object state) [0x0000d] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:1370
at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00071] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/referencesource/mscorlib/system/threading/executioncontext.cs:968
at System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/referencesource/mscorlib/system/threading/executioncontext.cs:910
at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem () [0x00021] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:1341
at System.Threading.ThreadPoolWorkQueue.Dispatch () [0x00074] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:899
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback () [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/referencesource/mscorlib/system/threading/threadpool.cs:1261

[jfversluis]

Not 100% sure, but I don't think you can have nulls in your DisplayAlert. Change this await DisplayAlert(Constants.AppName, "Player added automatically to weight screen", null, "OK"); to await DisplayAlert(Constants.AppName, "Player added automatically to weight screen", "OK");

[davidbuckleyni]

Yeah that ended it being it frigsake wonder didnt spot that