[1522] Where to write "bootstrap" code without main.js

I'm trying to rewrite an application from pure VueJS to NuxtJS because it seems to avoid a lot of boilerplate code. I have some code running in the VueJS created hook.

new Vue({
  el: '#app',
  ...,
  created () {
     // some code here
  }
})

Where is the best place to write this code? There is no entry point with NuxtJS I'm a bit lost...