UnhandledPromiseRejectionWarning when implementing RPC

[cbuchert]

Hey, guys. Thanks for being so active in supporting this library.

I'm running into an issue with the solutions provided in this thread. I'm running RabbitMQ 3.7.4 in Docker on OSX High Sierra. All JS is being run in Node 8. When I try to run the solution published by @facundoolano or my own code, I get the same error:

UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'once' of undefined

I isolated the EventEmitter and got a similar TypeError around channel.sendToQueue. This leads me to believe that when channel gets returned it's not the object I was anticipating (it looks like a promise). Any ideas on this? Here's my own implementation of the code, suffering from the same ailments.

const EventEmitter = require("events").EventEmitter;
const amqp = require("amqplib");
const uuid = require("uuid");

class RpcClient {
  constructor(server, socketOptions, requestQueue) {
    this.requestQueue = requestQueue;
    this.responseQueue = "amq.rabbitmq.reply-to";
    this.channel = amqp.connect("amqp://" + server, socketOptions)
      .then(connection => connection.createChannel())
      .then(channel => {
        const consumerOptions = {noAck: true};

        channel.responseEmitter = new EventEmitter();
        channel.responseEmitter.setMaxListeners(0);
        channel.consume(this.responseQueue,
          (message) => channel.responseEmitter.emit(message.properties.correlationId, message.content),
          consumerOptions);

        return channel;
      });
  }

  sendMessage(message) {
    return new Promise(resolve => {
      const correlationId = uuid.v4();
      const messageBuffer = new Buffer.from(JSON.stringify(message), "utf8");
      const publishOptions = {
        correlationId,
        replyTo: this.responseQueue,
      };

      this.channel.responseEmitter.once(correlationId, resolveJSON);
      this.channel.sendToQueue(this.requestQueue, messageBuffer, publishOptions);

      function resolveJSON(message) {
        resolve(JSON.parse(message));
      }
    });
  }
}

module.exports = RpcClient;

[cbuchert]

Oh man. Noob mistake with promises. Closing.