Conditionally exclude ModuleTypeLoaderNotFoundException.Desktop.cs

Prevents the desktop-specific exception file from being compiled for modern .NET target frameworks. This ensures correct multi-targeting behavior and aligns with the strategy to handle `.Desktop.cs` files introduced in previous refactorings.

Author: dansiegel

src/Avalonia/Prism.Avalonia/Prism.Avalonia.csproj

@@ -28,6 +28,7 @@ Prism.Avalonia helps you more easily design and build rich, flexible, and easy t
     <Compile Include="..\..\Wpf\Prism.Wpf\Navigation\Regions\**\*.cs" LinkBase="Navigation\Regions" />
 
     <Compile Remove="..\..\Wpf\Prism.Wpf\Interactivity\InvokeCommandAction.cs" />
+    <Compile Remove="..\..\Wpf\Prism.Wpf\Modularity\ModuleTypeLoaderNotFoundException.Desktop.cs" />
     <Compile Remove="..\..\Wpf\Prism.Wpf\Modularity\XamlModuleCatalog.cs" />
     <Compile Remove="..\..\Wpf\Prism.Wpf\Navigation\Regions\ItemMetadata.cs" />
     <Compile Remove="..\..\Wpf\Prism.Wpf\Navigation\Regions\Behaviors\BindRegionContextToDependencyObjectBehavior.cs" />

src/Wpf/Prism.Wpf/Prism.Wpf.csproj

@@ -23,6 +23,11 @@ Prism.Wpf helps you more easily design and build rich, flexible, and easy to mai
     <Reference Include="System.Configuration" />
   </ItemGroup>
 
+  <ItemGroup Condition=" !$(TargetFramework.StartsWith('net4')) ">
+    <Compile Remove="Modularity\ModuleTypeLoaderNotFoundException.Desktop.cs" />
+    <None Include="Modularity\ModuleTypeLoaderNotFoundException.Desktop.cs" />
+  </ItemGroup>
+
   <ItemGroup Condition=" $([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows' ">
     <Compile Remove="**\*.net45.cs" />
     <None Include="**\*.net45.cs" />