代码如下：

const path = require('path');
const VueLoaderPlugin = require('vue-loader/lib/plugin');

module.exports = {
  mode: 'development',
  entry: path.join(__dirname, 'src/index.js'),
  output: {
    filename: 'bundle.js',
    path: path.join(__dirname, 'dist')
  },
  module: {
    rules: [
      {
        test: /\.vue$/,
        loader: 'vue-loader'
      },
      {
        test: /\.css$/,
        use:[
          'style-loader',
          'css-loader'
        ]
      },
      {
        test: /\.js?$/,
        loader: 'babel-loader'
      },
      {
        test: /\.(jpg|jpeg|gif|bmp|png)$/,
        use:[
          {
            loader: 'url-loader',
            options: {
              limit: 1024,
              name: '[name]-[hash].[ext]'
            }
          }
        ]
      },
      {
        test: /\.styl/,
        use:[
          'style-loader',
          'css-loader,',
          'stylus-loader'
        ]
      }
    ]
  },
  plugins:[
    new VueLoaderPlugin()
  ]
}

import Vue from 'vue'
import App from './app.vue'

import './assets/styles/text.css'
import './assets/img/1.jpg'
import './assets/styles/test.styl'

const root = document.createElement("div");
document.body.appendChild(root);

new Vue({
    render:function(h){
        return h(App)
    }
}).$mount(root);

请问大家，这是什么原因呢？