Fix CmdPal gallery crash when extension has no homepage

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Gallery/ExtensionGalleryItemViewModel.cs

@@ -105,6 +105,13 @@ public ExtensionGalleryItemViewModel(
 
     public string? Homepage => _entry.Homepage;
 
+    // Validated, browser-openable homepage uri. Null when the entry has no
+    // homepage or it is not a web uri. NavigateUri bindings must use this
+    // (a Uri) rather than the raw Homepage string: x:Bind evaluates bindings
+    // regardless of element visibility, and converting a null/invalid string
+    // to Uri throws and crashes the page.
+    public Uri? HomepageUri => _homepageHttpUri;
+
     public Uri IconUri { get; }
 
     public ImageSource IconSource

src/modules/cmdpal/Microsoft.CmdPal.UI/Settings/ExtensionGalleryItemPage.xaml

@@ -232,7 +232,7 @@
                                 Grid.Row="3"
                                 Padding="0"
                                 AutomationProperties.AutomationId="CmdPal_GalleryItemPage_ViewRepository"
-                                NavigateUri="{x:Bind ViewModel.Homepage, Mode=OneWay}"
+                                NavigateUri="{x:Bind ViewModel.HomepageUri, Mode=OneWay}"
                                 ToolTipService.ToolTip="{x:Bind ViewModel.Homepage, Mode=OneWay}"
                                 Visibility="{x:Bind help:BindTransformers.BoolToVisibility(ViewModel.HasHomepage), Mode=OneWay, FallbackValue=Collapsed}">
                                 <StackPanel Orientation="Horizontal" Spacing="4">

src/modules/cmdpal/Tests/Microsoft.CmdPal.UI.ViewModels.UnitTests/ExtensionGalleryItemViewModelTests.cs

@@ -119,6 +119,7 @@ public void Constructor_IgnoresNonWebGalleryLinks()
         var viewModel = CreateViewModel(entry);
 
         Assert.IsFalse(viewModel.HasHomepage);
+        Assert.IsNull(viewModel.HomepageUri);
         Assert.IsFalse(viewModel.HasAuthorUrl);
         Assert.IsFalse(viewModel.HasUrlSource);
         Assert.IsFalse(viewModel.HasActionableSourceDetails);
@@ -131,6 +132,32 @@ public void Constructor_IgnoresNonWebGalleryLinks()
         Assert.IsFalse(viewModel.OpenInstallUrlCommand.CanExecute(null));
     }
 
+    [TestMethod]
+    public void Constructor_SetsHomepageUri_WhenHomepageIsWebUri()
+    {
+        var entry = CreateEntry(iconUrl: null);
+        entry.Homepage = "https://example.com/extension";
+
+        var viewModel = CreateViewModel(entry);
+
+        Assert.IsTrue(viewModel.HasHomepage);
+        Assert.AreEqual(new Uri("https://example.com/extension"), viewModel.HomepageUri);
+        Assert.IsTrue(viewModel.OpenHomepageCommand.CanExecute(null));
+    }
+
+    [TestMethod]
+    public void Constructor_LeavesHomepageUriNull_WhenHomepageIsMissing()
+    {
+        var entry = CreateEntry(iconUrl: null);
+        entry.Homepage = null;
+
+        var viewModel = CreateViewModel(entry);
+
+        Assert.IsFalse(viewModel.HasHomepage);
+        Assert.IsNull(viewModel.HomepageUri);
+        Assert.IsFalse(viewModel.OpenHomepageCommand.CanExecute(null));
+    }
+
     [TestMethod]
     public void Constructor_EnablesCopyCommand_WhenWinGetIdIsAvailable()
     {