Bug: emit won't resolve if the return value is undefined

[zhaoyao91]

I have a worker like this

worker.on("run", async () => {
  console.log("started");
  await run();
  console.log("finished");
});

however, await worker.emit('run') will never resolve. after changing the worker to

worker.on("run", async () => {
  console.log("started");
  await run();
  console.log("finished");

  return true
});

it resolves.

[zhaoyao91]

Great lib, saves me tons of life