Error: cannot find module './discord.js' on Heroku

This is my first time deploying on Heroku, and I've come across this hurdle that won't let me successfully deploy my Discord bot. I've been following a tutorial, and the creator seemed to deploy his project on the platform with no problem. However, as with most things, it hasn't been as straightforward the past hour.

The just being the Error: cannot find module './discord.js'

I tried the solution from this answer, but no luck.

Here is my package.json:

    "name": "booster-bot",
    "version": "1.0.0",
    "main": "index.js",
    "engines": {
        "node": "12.14.1",
        "npm": "6.13.4"
    },
    "repository": {
        "type": "git",
        "url": "git+link"
    },
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1",
        "start": "node bot.js",
        "devStart": "nodemon bot.js"
    },
    "keywords": [],
    "author": "",
    "license": "ISC",
    "description": "",
    "dependencies": {
        "dotenv": "^16.4.5",
        "requirements-txt": "^0.0.5"
    },
    "devDependencies": {
        "nodemon": "^3.1.4"
    }
}

As well as the block of code it points back to:

const {
  Client,
  Events,
  GatewayIntentBits,
  EmbedBuilder,
} = require("./discord.js");

const client = new Client({
  partials: ["GUILD_MEMBER"],
  intents: [
    GatewayIntentBits.Guilds,
    GatewayIntentBits.GuildMessages,
    GatewayIntentBits.MessageContent,
    GatewayIntentBits.GuildMembers,
    GatewayIntentBits.GuildPresences,
  ],
});

To note is that I initially did not have the ./ in the ./discord.js, but as per this other answer and my desperation, I thought I'd try it (didn't work). I also have the Procfile turned on and the requirements.txt installed, showing in this snippet on my package.json file:

    "name": "booster-bot",
    "version": "1.0.0",
    "lockfileVersion": 3,
    "requires": true,
    "packages": {
        "": {
            "name": "booster-bot",
            "version": "1.0.0",
            "license": "ISC",
            "dependencies": {
                "dotenv": "^16.4.5",
                "requirements-txt": "^0.0.5"
            },
            "devDependencies": {
                "nodemon": "^3.1.4"
            },
            "engines": {
                "node": "12.14.1",
                "npm": "6.13.4"
            }
        },

Thank you for any input/help!

Your package.json does not include discord.js

Run the command npm install discord.js --save to install it and add it to your package.json file.

Additionally, do not use relative path(./) to import a package, it would be best to import it using require('discord.js');