Laravel Mix V6

the new mix requires some extra setup to make things work especially that we are now using wp v5, so

• check mix UPGRADE.md

• under app.js

// instead of
window.Vue = require('vue')

// use 
import Vue from 'vue'

• under webpack.mix.js, add vue()

mix.js('resources/assets/js/app.js', 'public/js').vue()