System.NullReferenceException Current Activity is null when implementing Firebase Authentication

[Govern24]

Current Activity is null, ensure that the MainApplication.cs file is setting the CurrentActivity in your source code so Firebase Analytics can use it.

   private static MauiAppBuilder RegisterFirebaseServices(this MauiAppBuilder builder)
    {

        `builder.ConfigureLifecycleEvents(events =>
        {
#if IOS
            events.AddiOS(iOS => iOS.FinishedLaunching((app, launchOptions) => {
                CrossFirebase.Initialize(app, launchOptions, CreateCrossFirebaseSettings());
                return false;
            }));
#else
            events.AddAndroid(android => android.OnCreate((activity, state) =>
                CrossFirebase.Initialize(activity, state, CreateCrossFirebaseSettings())));
#endif
        });

        builder.Services.AddSingleton(_ => CrossFirebaseAuth.Current); //Exception is thrown on this line

        return builder;
    }

This is how my MainActivity looks like:

[Activity(Theme = "@style/Maui.SplashTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize | ConfigChanges.Density)]
public class MainActivity : MauiAppCompatActivity
{
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
    }

    protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
    {
        base.OnActivityResult(requestCode, resultCode, data);
        FirebaseAuthImplementation.HandleActivityResultAsync(requestCode, resultCode, data);

    }
}

This is the MainApplication class:

[Application]
public class MainApplication : MauiApplication
{
    public MainApplication(IntPtr handle, JniHandleOwnership ownership)
        : base(handle, ownership)
    {
    }

    protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
}

[TobiasBuchholz]

Hmm, I can't see any problem with your code so far. The android FirebaseAuthImplementation class uses the Microsoft.Maui.ApplicationModel.Platform.CurrentActivity object and this seems to be null for some reason, so maybe your Maui setup is wrongly configured somehow? Are you calling .UseMauiApp<App>() on the MauiAppBuilder in your MauiProgramm file?

[TobiasBuchholz]

Furthermore I've released a new version 1.3.0 which might fix the problem, see https://github.com/TobiasBuchholz/Plugin.Firebase/issues/67#issuecomment-1409304552