Fix MarkAsPendingWaitsForUpdates

src/LanguageServer/Impl/Indexing/MostRecentDocumentSymbols.cs

@@ -70,7 +70,7 @@ public async Task WorkAndSetTcs(Func<CancellationToken, Task<IReadOnlyList<Hiera
 
         public Task<IReadOnlyList<HierarchicalSymbol>> GetSymbolsAsync(CancellationToken ct = default) {
             lock (_syncObj) {
-                return _fileTcs.Task;
+                return _fileTcs.Task.WaitAsync(ct);
             }
         }
 
@@ -111,6 +111,7 @@ public void Dispose() {
                 }
                 _state = WorkQueueState.FinishedWork;
             }
+            _fileCts?.Dispose();
         }
 
         private async Task<IReadOnlyList<HierarchicalSymbol>> IndexAsync(IDocument doc, CancellationToken indexCt) {
@@ -150,6 +151,7 @@ private async Task<IReadOnlyList<HierarchicalSymbol>> ParseAsync(CancellationTok
 
         private void RenewTcs() {
             Check.InvalidOperation(Monitor.IsEntered(_syncObj));
+            _fileCts?.Dispose();
             _fileCts = new CancellationTokenSource();
             _fileTcs = new TaskCompletionSource<IReadOnlyList<HierarchicalSymbol>>();
         }