DEMO - Error of assign to read only 'exports' of object - caused by webpack and @babel/preset-env with special config

babel.config.js

module.exports = {
  presets: [
    [
      '@babel/env',
      {
        useBuiltIns: 'usage',
        modules: false
      }
    ]
  ]
}

index.js

module.exports = x.toString()

package.json

{
  "name": "demo",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "build": "webpack"
  },
  "keywords": [],
  "author": "luobotang",
  "license": "MIT",
  "dependencies": {
    "@babel/core": "^7.2.2",
    "@babel/polyfill": "^7.2.5",
    "@babel/preset-env": "^7.2.3",
    "babel-loader": "^8.0.5",
    "webpack": "^4.28.4",
    "webpack-cli": "^3.2.1"
  }
}

webpack.config.js

module.exports = {
  mode: 'production',
  entry: './src.js',
  module: {
    rules: [
      {
        test: /\.js$/,
        loader: 'babel-loader'
      }
    ]
  },
  optimization: {
    minimize: false
  }
}