Fails to babelify arrow syntax on npm run production

I just tried out Laravel mix and found that it would compile without errors with npm run dev. However, when I attempted to run npm run production, it failed on some arrow syntax in a .js file.

export function addRecords (records, newRecords, type) {
  if (!newRecords) {
    return
  }

  newRecords.forEach(newRecord => {
    addRecord(records, newRecord, type)
  })
}

And the error below refers to the newRecords.forEach(newRecord => { line above:

> node node_modules/cross-env/bin/cross-env.js NODE_ENV=production node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js

fallbackLoader option has been deprecated - replace with "fallback"
loader option has been deprecated - replace with "use"
 95% emitting
 ERROR  Failed to compile with 1 errors

 error

/js/app.a25a2e810095631e31db.js from UglifyJs
SyntaxError: Unexpected token: operator (>) [./resources/assets/js/vuex/helpers.js:6,21][/js/app.a25a2e810095631e31db.js:5690,32]

Sorry but failing on ES2015 arrow syntax is a bit of a deal breaker here.

[JeffreyWay]

Yep. You’re using a custom .babelrc file that doesn’t specify ES2015 compilation. And now you’re wondering why you’re not getting ES2015 compilation. 😃

{
    "presets": [
        ["es2015", { "modules": false }],
    ],
    "plugins": [
        "transform-object-rest-spread"
    ]
}

[wells]

Another note, including sourceMaps() in your webpack.mix.js file will double your production JS file output. I was getting 5MB with npm run dev and 1.8MB with npm run production. Once I removed the sourceMaps() call, everything went back to the same 662KB size produced by laravel elixir.

Totally looking forward to using code splitting as well. Thanks @JeffreyWay