Enable AOT/trimming warnings on TreeDataGrid project

Author: maxkatz6

src/Avalonia.Controls.TreeDataGrid/Avalonia.Controls.TreeDataGrid.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net5.0</TargetFramework>
+    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
     <IsPackable>True</IsPackable>
     <RootNamespace>Avalonia.Controls</RootNamespace>
   </PropertyGroup>
@@ -12,4 +12,19 @@
 
     <PackageReference Include="System.Reactive" Version="6.0.0" />
   </ItemGroup>
+
+  <!-- Trimming -->
+  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net6.0'))">
+    <SuppressTrimAnalysisWarnings>false</SuppressTrimAnalysisWarnings>
+    <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
+    <TrimmerSingleWarn>false</TrimmerSingleWarn>
+    <IsTrimmable>true</IsTrimmable>
+    <ILLinkTreatWarningsAsErrors>true</ILLinkTreatWarningsAsErrors>
+  </PropertyGroup>
+
+  <!-- AOT -->
+  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
+    <IsAotCompatible Condition="'$(IsAotCompatible)' == ''">true</IsAotCompatible>
+  </PropertyGroup>
+
 </Project>

src/Avalonia.Controls.TreeDataGrid/Models/TreeDataGrid/AnonymousRow.cs

@@ -15,10 +15,10 @@ namespace Avalonia.Controls.Models.TreeDataGrid
     internal class AnonymousRow<TModel> : IRow<TModel>, IModelIndexableRow
     {
         private int _modelIndex;
-        [AllowNull] private TModel _model;
+        private TModel? _model;
 
         public object? Header => _modelIndex;
-        public TModel Model => _model;
+        public TModel Model => _model!;
         public int ModelIndex => _modelIndex;
         public IndexPath ModelIndexPath => _modelIndex;