amqplib sendToQueue() is not sending messages to RabbitMQ

I am building a Typescript package around amqplib's Promise API to make it simpler for me to send messages between two RabbitMQ queues.

This is a method inside a class of said package that is responsible for sending a message to RabbitMQ. It's not actually sending messages, because I can't see them from CloudAMQP.

class PostOffice {
    connection: any;

    constructor(connection: any) {
        this.connection = connection;
    }

    //...

    // TMQMessage is an object that can be trivially serialized to JSON
    // The Writer class holds the channel because I'm having trouble
    // making Typescript class member updates stick after a method returns.
    async send(writer: Writer, message: TMQMessage) {
        //...RabbitMQ code begins here
        let channel = writer.stageConsume[0]; // This channel is created elsewhere
        
        // Queue is created here and I can see it in CloudAMQP.
        await channel.assertQueue(message.to + "/stage/1", {
            durable: true,
        }); // `message.to` is a string indicating destination, e.g. 'test/hello'
        
        // According to docs, the content should be converted to Buffer
        await channel.sendToQueue(message.to + "/stage/1", Buffer.from(JSON.stringify(message)));
        
        channel.close()
    }

}

This is a class I made that creates connections and channels, which is being used here:

import { Writer } from "./Writer";

export class ConnectionFactory {
    url: string;
    amqp: any;
    constructor(url: string) {
        this.url = url;
        this.amqp = require('amqplib');
    }

    async connect(timeout: number = 2000) {
        let connection = await this.amqp.connect(this.url, {
            // timeout for a message acknowledge.
            timeout, // Make the timeout 2s per now
        })
        return connection;
    }
    async createChannels(connection: any, writer: Writer) {
        //... relevant code starts here
        let stageChannels = [];
        stageChannels.push(await connection.createChannel())
        writer.stageConsume = stageChannels;
        return writer;
    }
}

}

My connection factory seems to be working properly, because I can see the connections from CloudAMQP's dashboard. Also I can see the Queues that have been created (asserted in my code) from the dashboard too. However, I am unable to get amqplib to send a message out to CloudAMQP.

Here's the (async) code I'm using to call my package:

let Cf = new ConnectionFactory(url)
let connection = await Cf.connect()
let writer = new Writer();

let message: TMQMessage = {
    //... message content in JSON
}

writer = await Cf.createChannels(connection, writer)
let po = new PostOffice(connection)
await po.send(writer, message)

What seems to be wrong?

Probably want to await the close method too. But in general I would recommend amqp-client.js (that also have TypeScript definitions), https://github.com/cloudamqp/amqp-client.js/