Merge pull request #22714 from dpoeschl/HandleMissingOOPProcess

Be resilient to the OOP process going away in TodoComments and DesignerAttribute processing

src/Features/Core/Portable/DesignerAttributes/AbstractDesignerAttributeService.cs

@@ -67,6 +67,11 @@ private async Task<KeepAliveSession> TryGetKeepAliveSessionAsync(RemoteHostClien
         private async Task<DesignerAttributeResult> ScanDesignerAttributesInRemoteHostAsync(RemoteHostClient client, Document document, CancellationToken cancellationToken)
         {
             var keepAliveSession = await TryGetKeepAliveSessionAsync(client, cancellationToken).ConfigureAwait(false);
+            if (keepAliveSession == null)
+            {
+                // The client is not currently running, so we don't know the state of the DesignerAttribute.
+                return new DesignerAttributeResult(designerAttributeArgument: null, containsErrors: false, applicable: false);
+            }
 
             var result = await keepAliveSession.TryInvokeAsync<DesignerAttributeResult>(
                 nameof(IRemoteDesignerAttributeService.ScanDesignerAttributesAsync),

src/Features/Core/Portable/TodoComments/AbstractTodoCommentService.cs

@@ -62,6 +62,11 @@ public async Task<IList<TodoComment>> GetTodoCommentsAsync(Document document, IL
             RemoteHostClient client, Document document, IList<TodoCommentDescriptor> commentDescriptors, CancellationToken cancellationToken)
         {
             var keepAliveSession = await TryGetKeepAliveSessionAsync(client, cancellationToken).ConfigureAwait(false);
+            if (keepAliveSession == null)
+            {
+                // The client is not currently running, so we don't have any results.
+                return SpecializedCollections.EmptyList<TodoComment>();
+            }
 
             var result = await keepAliveSession.TryInvokeAsync<IList<TodoComment>>(
                 nameof(IRemoteTodoCommentService.GetTodoCommentsAsync),