Java.Lang.NullPointerException: 'Attempt to invoke virtual method 'void android.app.Activity.requestPermissions(java.lang.String[], int)'

I have tried to request on App's class to request the READ_CONTACTS permissions but throws an exception Exception Java.Lang.NullPointerException: 'Attempt to invoke virtual method 'void android.app.Activity.requestPermissions(java.lang.String[], int)' on a null object reference'

{
    public App(SignalrMessenger signalrMessenger, ChatServicesSettings chatServicesSettings, ContactServices contactServices)
    {
        InitializeComponent();
        

        if (!IsPermissioGranted(Android.App.Application.Context, Manifest.Permission.ReadContacts))
        {
            RequestPermission(Android.App.Application.Context as Activity, new[] { Manifest.Permission.ReadContacts }).GetAwaiter().GetResult();
        }

        MauiApplicationServices.WasDatabaseUpdatedOnStartUp = contactServices.SynchronizeDbWithLocalContacts().GetAwaiter().GetResult();

        MainPage = new MainPage(signalrMessenger,chatServicesSettings);//new AppShell();
    }
    public bool IsPermissioGranted(Context ctx, string permission)
    {
        return ActivityCompat.CheckSelfPermission(ctx, permission)== Permission.Granted;
    }
    public async Task RequestPermission(Activity activity, params string[] permissions)
    {
        ActivityCompat.RequestPermissions(activity, permissions, 0);
        await Task.CompletedTask;
    }
}

So I wonder if there is possibly a way to ask for permission in an Activity and inject a service OnCreate method? since the default ctor is called in the MainActity app initialization

OnCreate method will be triggered as expected in MainActivity class.

You can ask for the permission inside MainActivity instead of App class.

Sample code

protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        if (ContextCompat.CheckSelfPermission(this, Manifest.Permission.Camera) == (int)Permission.Granted)
        {
            // We have permission, go ahead and use the camera.
        }
        else
        {
            ActivityCompat.RequestPermissions(this, new String[] { Manifest.Permission.Camera },0);
        }
    }

public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
    {
         base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    }