pino.final without a handler and stream.flushSync()

[javiertury]

I discovered that pino.final can be used without a handler, which I find very handy. Example:

const handler = (err) => {
  const finalLogger = pino.final(logger);
  
  if (err) finalLogger(err);
  process.exit(err ? 1 : 0);
};

But reading the code I found something that might be a bug and perhaps someone here can confirm it.

pino/lib/tools.js

Lines 463 to 478 in c57c258

	if (!hasHandler) {
	return finalLogger
	}
	return (err = null, ...args) => {
	try {
	stream.flushSync()
	} catch (e) {
	// it's too late to wait for the stream to be ready
	// because this is a final tick scenario.
	// in practice there shouldn't be a situation where it isn't
	// however, swallow the error just in case (and for easier testing)
	}
	return handler(err, finalLogger, ...args)
	}
	}

stream.flushSync() is only called before the handler is executed or after finalLogger is used. In the example above there is no handler and finalLogger is only called if there is an error, so when the process exits normally there is no call to stream.flushSync().

Perhaps the implemention when there is no handler should be this

  if (!hasHandler) {
    try {
      stream.flushSync()
    } catch (e) {
      // it's too late to wait for the stream to be ready
      // because this is a final tick scenario.
      // in practice there shouldn't be a situation where it isn't
      // however, swallow the error just in case (and for easier testing)
    }
    return finalLogger
  }

[mcollina]

Would you like to send a Pull Request to address this issue? Remember to add unit tests.

[github-actions]

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