docs: private void deliver() {
      try {
        deliverUnsafe();
      } catch (Throwable t) {
        // This should never happen. If does, it means we are in an inconsistent state and should
        // close the stream and further processing should be prevented. This is accomplished by
        // purposefully leaving the lock non-zero and notifying the outerResponseObserver of the
        // error. Care must be taken to avoid calling close twice in case the first invocation threw
        // an error.
        innerController.cancel();
        if (!finished) {
          outerResponseObserver.onError(t);
        }
      }
    }