putting uen:Region.Attached="True" in XAML when trying to use a TabBar for navaigation throws an exception

[GamerGirlandCo]

I've followed this tutorial to create TabBar navigation (with a few modifications), but when I navigate to the page containing the TabBar, I get this exception:

System.InvalidOperationException: 'No service for type 'Microsoft.UI.Xaml.Window' has been registered.'

Page XAML:

<Page
    x:Class="redacted.Presentation.Project"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:redacted.Presentation"
    xmlns:ctrl="using:redacted.Presentation.Controls"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    xmlns:uen="using:Uno.Extensions.Navigation.UI"
    xmlns:ext="using:redacted.Business.ShardExtensions"
    xmlns:utu="using:Uno.Toolkit.UI"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
	>
	<Grid>
		<SplitView IsPaneOpen="False" DisplayMode="Inline" x:Name="editorSplit" PanePlacement="Right">
			<SplitView.Pane>
				<ctrl:Editor x:Name="editPane"/>
			</SplitView.Pane>
			<Grid uen:Region.Attached="True">
				<Grid.ColumnDefinitions>
					<ColumnDefinition Width="Auto"/>
					<ColumnDefinition Width="*"/>
				</Grid.ColumnDefinitions>
				<utu:TabBar Grid.Column="0" SelectedIndex="0" Style="{StaticResource VerticalTabBarStyle}" uen:Region.Attached="True" >
					<utu:TabBar.SelectionIndicatorContent>
						<Border Width="3" VerticalAlignment="Stretch" HorizontalAlignment="Left" Background="#00e7e3" />
					</utu:TabBar.SelectionIndicatorContent>
					
					<utu:TabBar.Items>
						<utu:TabBarItem uen:Region.Name="List">list</utu:TabBarItem>
					</utu:TabBar.Items>
				</utu:TabBar>
			</Grid>
		</SplitView>
	</Grid>
</Page>

RegisterRoutes code:

private static void RegisterRoutes(IViewRegistry views, IRouteRegistry routes)
{
	views.Register(
		new ViewMap(ViewModel: typeof(ShellModel)),
		new ViewMap<MainPage, MainModel>(),
		new ViewMap<Presentation.Project, ProjectModel>(Data: new DataMap<G.Project>()),
		new ViewMap<ListPage, ListPageModel>(),
	);

	routes.Register(
		new RouteMap("", View: views.FindByViewModel<ShellModel>(),
			Nested: new RouteMap[]
			{
				new RouteMap("Main", View: views.FindByViewModel<MainModel>(), Nested: new RouteMap[]
				{
					new RouteMap("Project", View: views.FindByViewModel<ProjectModel>(),
					Nested: new RouteMap[]
					{
						new RouteMap("List", View: views.FindByViewModel<ListPageModel>())
					}
				)
				}),
			}
		)
	);
}

[nickrandolph]

Hi @GamerGirlandCo this looks like the window of the application hasn't been registered with the DI container that navigation uses. Did you start with an application created using the unoapp template (or the visual studio template wizard)?
Can you share the code you're using to setup the Host (typically in App.cs if you're using one of the uno templates)

[GamerGirlandCo]

Yes, I did use Visual Studio's Uno platform template.
OnLaunched code:

		protected async override void OnLaunched(LaunchActivatedEventArgs args)
		{
			var builder = this.CreateBuilder(args)
				// Add navigation support for toolkit controls such as TabBar and NavigationView
				.UseToolkitNavigation()
				.Configure(host => host
#if DEBUG
					// Switch to Development environment when running in DEBUG
					.UseEnvironment(Environments.Development)
#endif
					.UseLogging(configure: (context, logBuilder) =>
					{
						// Configure log levels for different categories of logging
						logBuilder
							.SetMinimumLevel(
								context.HostingEnvironment.IsDevelopment() ?
									LogLevel.Information :
									LogLevel.Warning)

							// Default filters for core Uno Platform namespaces
							.CoreLogLevel(LogLevel.Warning);

						// Uno Platform namespace filter groups
						// Uncomment individual methods to see more detailed logging
						//// Generic Xaml events
						//logBuilder.XamlLogLevel(LogLevel.Debug);
						//// Layout specific messages
						//logBuilder.XamlLayoutLogLevel(LogLevel.Debug);
						//// Storage messages
						//logBuilder.StorageLogLevel(LogLevel.Debug);
						//// Binding related messages
						//logBuilder.XamlBindingLogLevel(LogLevel.Debug);
						//// Binder memory references tracking
						//logBuilder.BinderMemoryReferenceLogLevel(LogLevel.Debug);
						//// RemoteControl and HotReload related
						//logBuilder.HotReloadCoreLogLevel(LogLevel.Information);
						//// Debug JS interop
						//logBuilder.WebAssemblyLogLevel(LogLevel.Debug);

					}, enableUnoLogging: true)
					.UseConfiguration(configure: configBuilder =>
						configBuilder
							.EmbeddedSource<App>()
							.Section<AppConfig>()
					)
					// Enable localization (see appsettings.json for supported languages)
					.UseLocalization()
					.ConfigureServices((context, services) =>
					{
						services.AddSingleton<IEntityService<G.Project>, EntityService<G.Project>>();
						services.AddSingleton<IEntityService<Section>, EntityService<Section>>();
						services.AddSingleton<IRecursiveEntityService<G.Task>, TaskEntityService>();
						services.AddSingleton<IRecursiveEntityService<Folder>, FolderEntityService>();


						services.AddDbContext<ShardContext>(options =>
						{
							string ti = Path.Join(ApplicationData.Current.LocalFolder.Path, "test.db");
							options.UseSqlite($"Data Source=test.db;Foreign Keys=True", o =>
							{
								o.UseQuerySplittingBehavior(QuerySplittingBehavior.SplitQuery);
							}).LogTo((a, b) => b > Microsoft.Extensions.Logging.LogLevel.Debug, (e) =>
							{
								System.Diagnostics.Debug.WriteLine(e);
							}).EnableSensitiveDataLogging(true);
						});
					})
					.UseNavigation(ReactiveViewModelMappings.ViewModelMappings, RegisterRoutes)
				);
			MainWindow = builder.Window;

			Host = await builder.NavigateAsync<Shell>();
		}