DetailsUrl can be null

Author: StanleyGoldman

src/GitHub.App/ViewModels/GitHubPane/PullRequestCheckViewModel.cs

@@ -48,7 +48,7 @@ public static IEnumerable<IPullRequestCheckViewModel> Build(IViewViewModelFactor
                 pullRequestCheckViewModel.Title = model.Context;
                 pullRequestCheckViewModel.Description = model.Description;
                 pullRequestCheckViewModel.Status = checkStatus;
-                pullRequestCheckViewModel.DetailsUrl = new Uri(model.TargetUrl);
+                pullRequestCheckViewModel.DetailsUrl = model.TargetUrl != null ? new Uri(model.TargetUrl) : null;
                 pullRequestCheckViewModel.AvatarUrl = model.AvatarUrl ?? DefaultAvatar;
                 pullRequestCheckViewModel.Avatar = model.AvatarUrl != null
                     ? new BitmapImage(new Uri(model.AvatarUrl))

src/GitHub.VisualStudio/Views/GitHubPane/PullRequestCheckView.xaml

@@ -45,8 +45,9 @@
         <!--
             <Label Grid.Column="3" HorizontalAlignment="Right" Content="{Binding Description}" ToolTip="{Binding Description}" />
         -->
-        <Label Grid.Column="3" HorizontalAlignment="Right">
-            <Hyperlink ToolTip="{Binding DetailsUrl}"  Command="{Binding OpenDetailsUrl}">Details</Hyperlink>
+        <Label Grid.Column="3" HorizontalAlignment="Right"
+               Visibility="{Binding DetailsUrl, Converter={ghfvs:NullToVisibilityConverter}}">
+            <Hyperlink ToolTip="{Binding DetailsUrl}" Command="{Binding OpenDetailsUrl}">Details</Hyperlink>
         </Label>
     </Grid>
 </local:GenericPullRequestCheckView>