Discord newbies annoying notify bot

notify-newbies.js

// Code released under Unlicense (https://unlicense.org/)

const Promise = require('bluebird');

const Discord = require('discord.js');
const fs = Promise.promisifyAll(require('fs'));

let client = new Discord.Client();

client.on('ready', async () => {
    return Promise.try(async () => {
        let guild = client.guilds.get('452308608990838814');

        if (guild == null) {
            throw new Error('Could not find guild');
        }

        await guild.fetchMembers();

        let newbiesRole = guild.roles.get('477152733921542155');

        if (newbiesRole == null) {
            throw new Error('Could not find role');
        }

        await guild.fetchMembers();

        if (newbiesRole.members.size == 0) {
            throw new Error('No newbies to message!');
        }

        let welcomeChannel = guild.channels.get('473856722717376527');

        if (welcomeChannel == null) {
            throw new Error('Could not find #welcome-area');
        }

        let oldMessageId = await fs.readFileAsync('lastMessageId', 'utf8');

        if (oldMessageId != null && oldMessageId.trim().length > 0) {
            let oldMessage = await welcomeChannel.fetchMessage(oldMessageId.trim());

            if (oldMessage != null) {
                await oldMessage.delete();
            }
        }

        await newbiesRole.setMentionable(true);

        await Promise.delay(1000);

        let message = await welcomeChannel.send('Hi ' + newbiesRole + ', than you all for joining! We would like to ask you to please introduce yourself in this channel. If you do so we can give you the role that suits you best. If you want to you can mention your portfolio / business website. We\'re excited to meet you!');

        await fs.writeFileAsync('lastMessageId', message.id);

        await Promise.delay(5000);

        await newbiesRole.setMentionable(false);

    }).finally(() => {
        process.exit();
    });
});

if (process.env.TOKEN == null || process.env.TOKEN.trim().length == 0) {
    throw new Error('No Discord token provided');
}

client.login(process.env.TOKEN);