Clean workflow to stop OutgoingMessage

[Skizu]

When using Zello Channels JS SDK for PTT a user may start and end a stream before getting a response from the start_stream event from either Session.startVoiceMessage() or direct calls to OutgoingMessage.start() in the case of autoStart: false. This sequences of events results in a less than desirable clean up task in the current implementation.

Consider the below snippet.

const outgoingMessage = session.startVoiceMessage();
await outgoingMessage.stop();

Due to the race condition with receiving the stream id, the clients socket traffic may look like so.

-> {"type":"audio","codec":"opus","codec_header":"gD4BPA==","packet_duration":60,"seq":3,"command":"start_stream"}
-> {"stream_id":null,"seq":3,"command":"stop_stream"}
<- {"stream_id":38793,"success":true,"seq":2}
<- {"error":"not enough params","seq":3}

A work around using a callback for startVoiceMessage also does not appear to be a viable option.

const callbacks = new WeakMap();

const outgoingMessage = session.startVoiceMessage((error, data) => {
  // on error, no action needed. Clean up handled by
  // `Session.sendCommandWithCallback()` rejecting the promise
  // referenced by `OutgoingMessage.start()` and calling
  // `this.stopRecording()`.
  if (error === null) {
    callbacks.delete(outgoingMessage);
    return;
  }

  const callback = callbacks.get(outgoingMessage);
  callback(error, data);
});

try {
  await outgoingMessage.stop();
} catch(error) {
  callbacks.set(outgoingMessage, (error, data) => {
    // `OutgoingMessage.currentMessageId` is set after the resolution
    // of this callback, as such we can not make use of
    // `OutgoingMessage.stop()`.
    session.stopStream({ stream_id: data.stream_id });
    
    // After callback `OutgoingMessage.start()` will then set
    // `currentMessageId` and call `OutgoingMessage.startRecording()`.
    // This is not desired as the call has been requested to stop.
    // An `Error` could be thrown to prevent this, ensuring recorder
    // is not started and left running, and sending data. However, this
    // leaves the `Session.sendCommandWithCallback()` Promise
    // unresolved.
    throw new Error();
  })
}

An alternate method is to add a listener for the recorder or encoder, and placing clean up code there, which is still not ideal solution.