Merge pull request #8078 from davidwengier/FixComment

src/Razor/src/Microsoft.VisualStudio.LanguageServerClient.Razor/DefaultRazorLanguageServerCustomMessageTarget.cs

@@ -1140,17 +1140,18 @@ public override Task<ImplementationResult> ImplementationAsync(DelegatedPosition
             request,
             cancellationToken).ConfigureAwait(false);
 
-        // Sometimes web tools will respond with a non-null response, of an array of diagnostics with a single element
-        // in it, but the actual diagnostics (and every other property) in that element are null. This confuses VS, and
-        // means we don't get squiggles for C# diagnostics, unless there are also Html diagnostics.
-        // This check ensures we catch that, and just return an empty result for Html diagnostics.
+        // If the delegated server wants to remove all diagnostics about a document, they will send back a response with an item, but that
+        // item will have null diagnostics (and every other property). We don't want to propagate that back out to the client, because
+        // it would make the client remove all diagnostics for the .razor file, including potentially any returned from other delegated
+        // servers.
         if (response?.Response is null or [{ Diagnostics: null }, ..])
         {
             return null;
         }
 
         return response.Response;
     }
+
     private async Task<TResult?> DelegateTextDocumentPositionRequestAsync<TResult>(DelegatedPositionParams request, string methodName, CancellationToken cancellationToken)
     {
         var delegationDetails = await GetProjectedRequestDetailsAsync(request, cancellationToken).ConfigureAwait(false);