Removed demo project pending upgrade, resolved some test errors

Author: matt-goldman

Plugin.Maui.SmartNavigation.slnx

@@ -1,9 +1,6 @@
 <Solution>
   <Folder Name="/Solution Items/" />
   <Folder Name="/src/">
-    <Project Path="src/DemoProject/DemoProject.csproj">
-      <Deploy Solution="Debug|*" />
-    </Project>
     <Project Path="src/Plugin.Maui.SmartNavigation.Attributes/Plugin.Maui.SmartNavigation.Attributes.csproj" />
     <Project Path="src/Plugin.Maui.SmartNavigation.MopupsExtensions/Plugin.Maui.SmartNavigation.MopupsExtensions.csproj" />
     <Project Path="src/Plugin.Maui.SmartNavigation.SourceGenerators/Plugin.Maui.SmartNavigation.SourceGenerators.csproj" />

src/Plugin.Maui.SmartNavigation/Services/NavigationManager.cs

@@ -6,6 +6,7 @@
 
 namespace Plugin.Maui.SmartNavigation.Services;
 
+#nullable enable
 internal partial class NavigationManager(INavigation navigation) : INavigationManager
 {
     public async Task GoBackAsync()
@@ -49,7 +50,7 @@ public async Task GoToAsync(Route route, string? query = null)
 
     public Task PopModalAsync() => navigation.PopModalAsync();
 
-    public Task PushAsync<TPage>(object args = null) where TPage : Page => navigation.PushAsync<TPage>(args);
+    public Task PushAsync<TPage>(object? args = null) where TPage : Page => navigation.PushAsync<TPage>(args);
 
-    public Task PushModalAsync<TPage>(object args = null) where TPage : Page => navigation.PushModalAsync<TPage>(args);
+    public Task PushModalAsync<TPage>(object? args = null) where TPage : Page => navigation.PushModalAsync<TPage>(args);
 }

tests/Plugin.Maui.SmartNavigation.IntegrationTests/Tests/ErrorHandlingTests/ErrorHandlingTests.cs

@@ -113,6 +113,7 @@ public async Task PopAsync_OnEmptyNavigationStack_ShouldThrowInvalidOperationExc
         async Task act() => await navigationMock.Object.PopAsync();
 
         // Assert
+        var ex = await Should.ThrowAsync<InvalidOperationException>(act);
     }
 
     [Fact]