Compatible to IE9

yarn add babel-polyfill

yarn add es6-promise

module.exports = {
  entry: {
    app: ["./src/main.js"]
  },

Changed

module.exports = {
  entry: {
    app: ["babel-polyfill", "./src/main.js"]
  },

main.js

import 'babel-polyfill'
import 'es6-promise/auto'