INavigationService Extensions for thread safe + error handled navigation

NavigationServiceExtensons.cs

using System;
using System.Threading.Tasks;
using Prism;
using Prism.Navigation;
using Xamarin.Forms;
using Xamarin.Essentials.Interfaces;
using Xamarin.Essentials.Implementation;

public static class NavigationServiceExtensions
{
    public static IMainThread ImplementedInstance { get; } = new MainThreadImplementation();

    public static async Task NavigateOnMainThread(this INavigationService navigationService, Func<Task<INavigationResult>> action, IMainThread mainThread)
    {
        INavigationResult result = null;

        if (mainThread is null)
        {
            mainThread = ImplementedInstance;
        }

        if (mainThread.IsMainThread)
        {
            result = await action.Invoke();
        }
        else
        {
            result = await mainThread.InvokeOnMainThreadAsync(action);
        }

        navigationService.HandleNavigationResult(result);
    }

    public static async Task TryNavigateAsync(this INavigationService navigationService, Uri uri,
        INavigationParameters parameters = null,
        IMainThread mainThread = null)
    {
        Func<Task<INavigationResult>> navigation = () => navigationService.NavigateAsync(uri, parameters);

        await NavigateOnMainThread(navigationService, navigation, mainThread);
    }

    public static async Task TryNavigateModallyAsync(this INavigationService navigationService, Uri uri,
        INavigationParameters parameters = null,
        IMainThread mainThread = null)
    {
        Func<Task<INavigationResult>> navigation = () => navigationService.NavigateAsync(uri, parameters, true, true);

        await NavigateOnMainThread(navigationService, navigation, mainThread);
    }

    public static async Task TryNavigateAsync(this INavigationService navigationService, string path,
        INavigationParameters parameters = null,
        IMainThread mainThread = null)
    {
        Func<Task<INavigationResult>> navigation = () => navigationService.NavigateAsync(path, parameters);

        await NavigateOnMainThread(navigationService, navigation, mainThread);
    }

    public static async Task TryNavigateModallyAsync(this INavigationService navigationService, string path,
        INavigationParameters parameters = null,
        IMainThread mainThread = null)
    {
        Func<Task<INavigationResult>> navigation = () => navigationService.NavigateAsync(path, parameters, true, true);

        await NavigateOnMainThread(navigationService, navigation, mainThread);
    }

    public static async Task TryNavigateBackAsync(this INavigationService navigationService,
        INavigationParameters parameters = null,
        IMainThread mainThread = null)
    {
        Func<Task<INavigationResult>> navigation = () => navigationService.GoBackAsync(parameters);

        await NavigateOnMainThread(navigationService, navigation, mainThread);
    }

    public static async Task TryClearPopupStackAsync(this INavigationService navigationService,
        IMainThread mainThread = null)
    {
        Func<Task<INavigationResult>> navigation = () => navigationService.ClearPopupStackAsync();

        await NavigateOnMainThread(navigationService, navigation, mainThread);
    }

    private static async void HandleNavigationResult(this INavigationService navigationService,
        INavigationResult navigationResult)
    {
        if (navigationResult is null) // This case should only occur in incorrectly setup unit tests
            return;

        if (!navigationResult.Success)
        {
            Exception ex = new InvalidNavigationException();
            if (navigationResult.Exception != null)
                ex = navigationResult.Exception;

            var p = new NavigationParameters()
            {
                { ParameterConstants.ExceptionError, ex }
            };

            var nav = await navigationService.NavigateAsync("NavigationErrorPage", p);

            if (!nav.Success)
            {
                SetMainPageFromException(ex);
            }
        }
    }

    private static void SetMainPageFromException(Exception ex)
    {
        var layout = new StackLayout
        {
            Padding = new Thickness(40)
        };
        layout.Children.Add(new Label
        {
            Text = ex?.GetType()?.Name ?? "Unknown Error encountered",
            FontAttributes = FontAttributes.Bold,
            HorizontalOptions = LayoutOptions.Center
        });

        layout.Children.Add(new ScrollView
        {
            Content = new Label
            {
                Text = $"{ex}",
                LineBreakMode = LineBreakMode.WordWrap
            }
        });

        PrismApplicationBase.Current.MainPage = new ContentPage
        {
            Content = layout
        };
    }
}