TaskService contained synchronous listener throws but discarded returned promises. An async TaskDoneListener could therefore reject as an unhandled process rejection even though the API promises per-listener containment.
Allow listeners to return PromiseLike<void> and attach a rejection handler to each result without awaiting it. This logs asynchronous failures independently while preserving the observation-only contract: later listeners, task waiters, and teardown are not delayed. Add a regression test and synchronize the public docs and generated API declaration.
Tianyi Cui
d462348556