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Handling disposal in async code ​

Problem ​

Your async function is awaiting a bus event when the bus gets disposed mid-flight. Without explicit handling, wait() rejects with BusDisposedError and the unhandled rejection crashes the caller.

Solution ​

Use BusDisposedError for instanceof checks instead of string matching:

ts
import { BusDisposedError } from '@vielzeug/eventit';

async function waitForLogin(bus: Bus<AppEvents>) {
  try {
    const { userId } = await bus.wait('user:login', AbortSignal.timeout(10_000));
    return userId;
  } catch (err) {
    if (err instanceof BusDisposedError) return null; // bus torn down — graceful exit
    throw err; // timeout or unexpected error — propagate
  }
}

Pitfalls ​

  • Checking err.message === 'Bus is disposed' instead of err instanceof BusDisposedError breaks when the message changes or the class is minified. Always use instanceof.
  • Catching BusDisposedError without re-throwing other errors silently swallows unexpected failures. Only catch the specific class and let everything else propagate.
  • A disposed bus silently drops all emit() calls. Code that expects post-disposal emissions to arrive will hang indefinitely.