我安装了css-loader style-loader

// webpack.config.js
rules: [
      { test: /\.vue$/, loader: 'vue-loader' },
      { test: /\.js$/, loader: 'babel-loader', exclude: /node_modules/ },
      { test: /\.css$/, loader: 'style-loader!css-loader' },
      {  test: /\.(png|jpg|gif|svg)$/, loader: 'file-loader', options: { name: '[name].[ext]?[hash]' } }
    ]

// main.js
import Vue from 'vue'
import ElementUI from 'element-ui'
import 'element-ui/lib/theme-default/index.css'
import App from './App.vue'

Vue.use(ElementUI)

new Vue({
  el: '#app',
  render: h => h(App)
})

报错如下图