message: Don't use finally
diff: @@ -15,7 +15,7 @@ class PromiseTracker {
  addPromise<T>(promise: Promise<T>): Promise<T> {
  this.numTracked++;
  this.subject.next(true);
  - promise.finally(this.countDown);
  + promise.then(this.countDown, this.countDown);
  return promise;
  }
  