I am trying to make a discord bot and I haven't used slash commands before as I haven't made a bot in a while, and I am getting this error when trying to register my commands:

DiscordAPIError[50035]: Invalid Form Body
application_id[NUMBER_TYPE_COERCE]: Value "undefined" is not snowflake.
guild_id[NUMBER_TYPE_COERCE]: Value "undefined" is not snowflake.
    at SequentialHandler.runRequest (/home/runner/blkt/node_modules/@discordjs/rest/dist/index.js:708:15)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async SequentialHandler.queueRequest (/home/runner/blkt/node_modules/@discordjs/rest/dist/index.js:511:14) {
  rawError: {
    code: 50035,
    errors: { application_id: [Object], guild_id: [Object] },
    message: 'Invalid Form Body'
  },
  code: 50035,
  status: 400,
  method: 'put',
  url: 'https://discord.com/api/v9/applications/undefined/guilds/undefined/commands',
  requestBody: { files: undefined, json: [ [Object] ] }
}

I am following the discordjs.guide tutorial and my deploy-commands.js code is this:

const token = process.env['token'];
const clientId = process.env['clientid'];
const guildId = process.env['testguildid']
const fs = require('node:fs');
const path = require('node:path');
const { REST } = require('@discordjs/rest');
const { Routes } = require('discord-api-types/v9');

const commands = [];
const commandsPath = path.join(__dirname, 'commands');
const commandFiles = fs.readdirSync(commandsPath).filter(file => file.endsWith('.js'));

for (const file of commandFiles) {
    const filePath = path.join(commandsPath, file);
    const command = require(filePath);
    commands.push(command.data.toJSON());
}

const rest = new REST({ version: '9' }).setToken(token);

rest.put(Routes.applicationGuildCommands(clientId, guildId), { body: commands })
    .then(() => console.log('Successfully registered application commands.'))
    .catch(console.error);