Fixes the dependency loop.

Gamenight.Ui/Gamenight.Ui/App.axaml.cs

@@ -27,6 +27,9 @@ public partial class App : Application
     {
         // Register all the services needed for the application to run
         var collection = new ServiceCollection();
+
+        new AppBootstrapper(collection, new RoutingState());
+
         var state = new GamenightState();
         collection.AddSingleton(state);
         
@@ -38,7 +41,6 @@ public partial class App : Application
         );
         collection.AddSingleton(gamenightApi);
         collection.AddSingleton<MainViewModel>();
-        collection.AddSingleton<IScreen>(sp => sp.GetRequiredService<MainViewModel>());
         collection.AddSingleton<HeaderViewModel>();
         collection.AddSingleton<SideBarViewModel>();
         collection.AddSingleton<GamenightsViewModel>();
@@ -51,6 +53,8 @@ public partial class App : Application
             collection.AddSingleton<MainView>();
         }
 
+        RxApp.SuspensionHost.GetAppState<AppBootstrapper>();
+
         ServiceProvider = collection.BuildServiceProvider();
 
         var mainViewModel = ServiceProvider.GetRequiredService<MainViewModel>();

Gamenight.Ui/Gamenight.Ui/AppBootstrapper.cs

@@ -0,0 +1,26 @@
+using ReactiveUI;
+using Splat;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.Metrics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Gamenight.Ui
+{
+    public  class AppBootstrapper : ReactiveObject, IScreen
+    {
+        public AppBootstrapper(ServiceCollection collection, RoutingState router)
+        {
+            Router = router ?? new RoutingState();
+
+            collection.AddSingleton<IScreen>(this);
+        }
+
+
+
+        public RoutingState Router { get; }
+    }
+}

Gamenight.Ui/Gamenight.Ui/ViewModels/GamenightsViewModel.cs

@@ -16,9 +16,4 @@ public class GamenightsViewModel : ReactiveObject, IRoutableViewModel
         GamenightApi = gamenightApi;
         HostScreen = hostScreen;
     }
-
-    public GamenightsViewModel()
-    {
-        throw new NotImplementedException();
-    }
 }

Gamenight.Ui/Gamenight.Ui/ViewModels/MainViewModel.cs

@@ -6,7 +6,7 @@ using ReactiveUI.SourceGenerators;
 
 namespace Gamenight.Ui.ViewModels;
 
-public partial class MainViewModel : ReactiveObject, IScreen
+public partial class MainViewModel : ReactiveObject
 {
     [ObservableAsProperty]
     private string _greeting = "Welcome to Avalonia!";
@@ -14,17 +14,19 @@ public partial class MainViewModel : ReactiveObject, IScreen
     public HeaderViewModel HeaderViewModel { get; }
     public SideBarViewModel SideBarViewModel { get; }
 
-    public RoutingState Router { get; } = new RoutingState();
-
     [ObservableAsProperty]
     private IReactiveCommand _loginCommand;
 
-    public MainViewModel(IGamenightApi gamenightApi, HeaderViewModel headerViewModel, SideBarViewModel sideBarViewModel)
+    [ObservableAsProperty] 
+    private IScreen _screen;
+
+    public MainViewModel(IGamenightApi gamenightApi, IScreen screen, HeaderViewModel headerViewModel, SideBarViewModel sideBarViewModel)
     {
         GamenightApi = gamenightApi;
+        _screen = screen;
+
         HeaderViewModel = headerViewModel;
         SideBarViewModel = sideBarViewModel;
-        SideBarViewModel.Screen = this;
 
         _loginCommand = ReactiveCommand.Create(Test);
     }

Gamenight.Ui/Gamenight.Ui/ViewModels/SideBarViewModel.cs

@@ -6,6 +6,13 @@ namespace Gamenight.Ui.ViewModels;
 
 public partial class SideBarViewModel : ReactiveObject
 {
+    public SideBarViewModel(IScreen screen, GamenightsViewModel gamenightsViewModel)
+    {
+        Screen = screen;
+        PushViewModel = ReactiveCommand.CreateFromObservable((IRoutableViewModel x) => Screen.Router.Navigate.Execute(x));
+        GamenightsViewModel = gamenightsViewModel;
+    }
+
     public IReactiveCommand<IRoutableViewModel, IRoutableViewModel> PushViewModel
     {
         get;
@@ -18,12 +25,5 @@ public partial class SideBarViewModel : ReactiveObject
         set => this.RaiseAndSetIfChanged(ref field, value);
     }
 
-    public IScreen Screen { get; set; }
-        
-
-    public SideBarViewModel(GamenightsViewModel gamenightsViewModel)
-    {
-        PushViewModel = ReactiveCommand.CreateFromObservable((IRoutableViewModel x) => Screen.Router.Navigate.Execute(x));
-        GamenightsViewModel = gamenightsViewModel;
-    }
+    private IScreen Screen { get; }
 }

Gamenight.Ui/Gamenight.Ui/Views/GamenightsView.axaml

@@ -6,9 +6,10 @@
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
              x:Class="Gamenight.Ui.Views.GamenightsView"
              x:DataType="vm:GamenightsViewModel">
-  <Design.DataContext>
-    <!-- This only sets the DataContext for the previewer in an IDE,
+    <Design.DataContext>
+        <!-- This only sets the DataContext for the previewer in an IDE,
          to set the actual DataContext for runtime, set the DataContext property in code (look at App.axaml.cs) -->
-    <vm:GamenightsViewModel />
-  </Design.DataContext>
+        <vm:GamenightsViewModel />
+    </Design.DataContext>
+    <Label Content="LOL"></Label>
 </UserControl>

Gamenight.Ui/Gamenight.Ui/Views/MainView.axaml

@@ -26,7 +26,7 @@
         <ColumnDefinition Width="*"/>
       </Grid.ColumnDefinitions>
       <views:SideBarView Grid.Column="0" DataContext="{Binding SideBarViewModel}"/>
-      <reactiveUi:RoutedViewHost Grid.Column="1" Router="{Binding Router}">
+      <reactiveUi:RoutedViewHost Grid.Column="1" Router="{Binding Screen.Router}">
         <reactiveUi:RoutedViewHost.DefaultContent>
           <TextBlock Text="Default content"
                      HorizontalAlignment="Center"