Discord.js: (node:4976) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated

Question

Below you'll find my code, and then the error message I'm getting. I'm not sure why I'm getting this error or how to resolve the issue.

const Discord = require("discord.js");
const client = new Discord.Client();
const DisTube = require("distube");
const distube = new DisTube(client, { searchSongs: false, emitNewSongOnly: true });
const prefix = "!";

client.on("ready", () => {
    console.log(`${client.user.tag} Está Online`);
});

client.on("message", async (message) => {
    if (message.author.bot) return;
    if (!message.content.startsWith(prefix)) return;
    const args = message.content.slice(prefix.length).trim().split(/ +/g);
    const command = args.shift();

    // Queue status template
    const status = (queue) =>
        `Volume: \`${queue.volume}%\` | Filter: \`${queue.filter || "Off"}\` | Loop: \`${queue.repeatMode ? (queue.repeatMode == 2 ? "All Queue" : "This Song") : "Off"}\` | Autoplay: \`${queue.autoplay ? "On" : "Off"}\``;

    // DisTube event listeners, more in the documentation page
    distube
        .on("playSong", (message, queue, song) => message.channel.send(`Playing \`${song.name}\` - \`${song.formattedDuration}\`\nRequested by: ${song.user}\n${status(queue)}`))
        .on("addSong", (message, queue, song) => message.channel.send(`Added ${song.name} - \`${song.formattedDuration}\` to the queue by ${song.user}`))
        .on("playList", (message, queue, playlist, song) =>
            message.channel.send(`Play \`${playlist.name}\` playlist (${playlist.songs.length} songs).\nRequested by: ${song.user}\nNow playing \`${song.name}\` - \`${song.formattedDuration}\`\n${status(queue)}`)
        )
        .on("addList", (message, queue, playlist) => message.channel.send(`Added \`${playlist.name}\` playlist (${playlist.songs.length} songs) to queue\n${status(queue)}`))
        // DisTubeOptions.searchSongs = true
        .on("searchResult", (message, result) => {
            let i = 0;
            message.channel.send(`**Choose an option from below**\n${result.map((song) => `**${++i}**. ${song.name} - \`${song.formattedDuration}\``).join("\n")}\n*Enter anything else or wait 60 seconds to cancel*`);
        })
        // DisTubeOptions.searchSongs = true
        .on("searchCancel", (message) => message.channel.send(`Searching canceled`))
        .on("error", (message, e) => {
            console.error(e);
            message.channel.send("An error encountered: " + e);
        });
    if ((command = "play")) {
        if (!args[0]) return message.channel.send("Voce Precisa Falar Algo Para Eu Tocar");
        if (!message.member.voice.channel) return message.channel.send("Entre Em Um Canal De Voz Primeiro");
        distube.play(message, args.join(" "));
    }
    if ((command = "pause")) {
        const bot = message.guild.members.cache.get(client.user.id);
        if (!message.member.voice.channel) return message.channel.send("Entre Em Um Canal De Voz Primeiro");
        if (bot.voice.channel !== message.member.voice.channel) return message.channel.send("Você Não Está No Mesmo Canal De Voz!");
        distube.stop(message);
        message.channel.send("Você Parou A Musica");
    }
});

client.login(process.env.TOKEN);

The result is the following error message:

**(node:4976) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
(node:4976) UnhandledPromiseRejectionWarning: TypeError: Assignment to constant variable.
(node:4976) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)**

Can someone explain to me:

1. Why am I getting this error message?
2. How to I begin to properly debug this?
3. And if there is a quick example / solution.

Answer 1

As Skulaurun said in the comments, you need to use == or === for comparison instead of = , which is the assignment operator.

The problem in your code is in these lines:

if ((command = "play")) { ... }

Since you're only using one = , node interprets this as you wanting to assign the value of "play" to command , which is a constant and cannot be changed, hence the error. You want to be using == or === for comparison, like:

if (command === "play") { ... }

Same goes for if ((command = "pause")) , which has the same issue.