Fix a crash in the async relay command page

Author: Sergio0694

samples/MvvmSample.Core/MvvmSample.Core.csproj

@@ -45,7 +45,7 @@
     </Content>
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="CommunityToolkit.Mvvm" Version="7.0.3" />
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.0.0-preview2" />
     <PackageReference Include="Nito.AsyncEx.Coordination" Version="5.1.2" />
     <PackageReference Include="Refit" Version="6.3.2" />
   </ItemGroup>

samples/MvvmSampleUwp/Converters/TaskResultConverter.cs

@@ -0,0 +1,34 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Threading.Tasks;
+using Windows.UI.Xaml.Data;
+
+namespace Microsoft.Toolkit.Uwp.UI.Converters
+{
+    /// <summary>
+    /// Custom version of the converter from the Toolkit, with a bug fix.
+    /// This should be moved over to the Toolkit in the next release.
+    /// </summary>
+    public sealed class TaskResultConverter2 : IValueConverter
+    {
+        /// <inheritdoc/>
+        public object Convert(object value, Type targetType, object parameter, string language)
+        {
+            if (value is Task task)
+            {
+                return task.GetResultOrDefault();
+            }
+
+            return null;
+        }
+
+        /// <inheritdoc/>
+        public object ConvertBack(object value, Type targetType, object parameter, string language)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

samples/MvvmSampleUwp/MvvmSampleUwp.csproj

@@ -120,12 +120,13 @@
     <Compile Include="App.xaml.cs">
       <DependentUpon>App.xaml</DependentUpon>
     </Compile>
-    <Compile Include="Controls\DocumentationBlock.cs" >
+    <Compile Include="Controls\DocumentationBlock.cs">
       <DependentUpon>DocumentationBlock.xaml</DependentUpon>
     </Compile>
-    <Compile Include="Controls\InteractiveSample.cs" >
+    <Compile Include="Controls\InteractiveSample.cs">
       <DependentUpon>InteractiveSample.xaml</DependentUpon>
     </Compile>
+    <Compile Include="Converters\TaskResultConverter.cs" />
     <Compile Include="Helpers\TitleBarHelper.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Services\FileService.cs" />

samples/MvvmSampleUwp/Views/AsyncRelayCommandPage.xaml

@@ -21,7 +21,7 @@
         </core:EventTriggerBehavior>
     </interactivity:Interaction.Behaviors>
     <Page.Resources>
-        <converters:TaskResultConverter x:Key="TaskResultConverter" />
+        <converters:TaskResultConverter2 x:Key="TaskResultConverter" />
     </Page.Resources>
 
     <ScrollViewer Padding="{StaticResource DocumentationPageContentPadding}" CanContentRenderOutsideBounds="True">