FormData using BusBoy for firebase works in serve but not in deploy

Question

Situation

I have a firebase function that updates the user image.

Problem

When I run locally my function using firebase serve, I successfully upload the image to firestore using Postman. However, when I run firebase deploy and I try to upload the image using Postman, I get a 500 Internal Server Error. The other functions (not dealing with FormData, just json) work perfectly when I deploy them.

I don't understand why it works locally, but not on deploy when I am doing the exact same thing. Not sure if this is something in the config I am missing, or if I am doing something wrong. Any help would be appreciated!

Code users.js

const { admin, db, firebase } = require('../util/admin');
const config = require('../util/config');

exports.postUserImage = (req, res) => {
  const BusBoy = require('busboy');
  const path = require('path');
  const os = require('os');
  const fs = require('fs');

  let imgFileName;
  let imgToBeUploaded = {};
  const busboy = new BusBoy({ headers: req.headers });

  busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
    // Invalid file type
    if (mimetype !== 'image/jpeg' && mimetype !== 'image/png') {
      return res.status(400).json({ error: 'Invalid file type' });
    }
    // Extract img extension
    const imgDotLength = filename.split('.').length;
    const imgExtension = filename.split('.')[imgDotLength - 1];
    // Create img file name
    imgFileName = `${Math.round(Math.random() * 1000000)}.${imgExtension}`;
    // Create img path
    const filepath = path.join(os.tmpdir(), imgFileName);
    // Create img object to be uploaded
    imgToBeUploaded = { filepath, mimetype };
    // Use file system to create the file
    file.pipe(fs.createWriteStream(filepath));
  });
  busboy.on('finish', () => {
    admin
      .storage()
      .bucket()
      .upload(imgToBeUploaded.filepath, {
        resumable: false,
        metadata: {
          metadata: {
            contentType: imgToBeUploaded.mimetype
          }
        }
      })
      .then(() => {
        // Create img url to add to our user
        const imgUrl = `https://firebasestorage.googleapis.com/v0/b/${config.storageBucket}/o/${imgFileName}?alt=media`;
        // Add img url to user document
        return db.doc(`/users/${req.user.handle}`).update({ imgUrl });
      })
      .then(() => {
        return res.json({ message: 'Image uploaded succesfully' });
      })
      .catch((err) => {
        console.error(err);
        return res.status(500).json({ error });
      });
  });
  busboy.end(req.rawBody);
};

index.js

const { app, functions } = require('./util/admin');
const FirebaseAuth = require('./util/firebaseAuth');
const {
  postUserImage,
} = require('./handlers/users');
app.post('/user/image', FirebaseAuth, postUserImage);