Как сделать сборку webpack для frontend?

Разбираюсь с webpack, столкнулся с ошибкой

package.json

{
  "name": "webpack2",
  "version": "1.0.0",
  "description": "",
  "main": "src/app.js",
  "scripts": {
    "build": "webpack",
    "start": "webpack --watch"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "css-loader": "^0.28.11",
    "extract-text-webpack-plugin": "^3.0.2",
    "node-sass": "^4.9.0",
    "sass-loader": "^7.0.3",
    "style-loader": "^0.21.0",
    "webpack": "^4.12.0",
    "webpack-cli": "^3.0.4"
  }
}

webpack.config.js

const path = require('path');
const ExtractTextPlugin = require("extract-text-webpack-plugin");
module.exports = {
  entry: './src/app.js',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        test: /\.scss$/,
        use: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          use: ['css-loader', 'sass-loader']
        })
      }
    ]
  },
  plugins: [
    new ExtractTextPlugin('style.css')
  ]
};