Node: Can't figure out where this error is coming from! 'SyntaxError: Unexpected token )'

I keep getting a SyntaxError: Unexpected token )' error for the following code:

const bCrypt = require('bcrypt-nodejs');
const LocalStrategy = require('passport-local').Strategy;

module.exports = (passport, user) => {
  const User = user;

  passport.use(
    'local-signup',
    new LocalStrategy({
        usernameField: 'email',
        passwordField: 'password',
        passReqToCallback: true, // pass back req to callback
      },
      (req, email, password, done) => {
        const generateHash = password => bCrypt.hashSync(password, bCrypt.genSaltSync(8), null);

        User.findOne({
          where: {
            email,
          },
        }).then(user => {
          if (user) {
            return done(null, false, {
              message: 'That email is already taken',
            });
          }

          const userPassword = generateHash(password);
          const data = {
            email,
            username: req.body.username,
            password: userPassword,
          };

          User.create(data).then((newUser) => !newUser ? done(null, false) : done(null, newUser));
          // creates user, callback with user that exists or false if something went wrong
        });
      },
    ),
  );
};

It really only started after I put arrow functions in. I think I'm missing something syntax-wise. I'm using the airbnb style guide & linter btw. Running node lts. VS Code doesn't give any parsing errors either in the editor itself. This is the error log in the terminal:

Also, this line in the terminal: at require (internal/module.js:20:19) at Object.<anonymous> (/Users/Rishi/www/Courses/bootcamp/blogapp/app/routes/home.js:8:1)

EDIT -- The code works when transpiled to ES2015 via Babel. I'm still curious why it isn't working with the ES6 syntax.

via Rishi Speets