以下是webpack的配置

var path = require('path')
var webpack = require('webpack')
var HtmlWebpackPlugin = require('html-webpack-plugin')
var FriendlyErrorsPlugin = require('friendly-errors-webpack-plugin')
var ExtractTextPlugin = require('extract-text-webpack-plugin')
var CleanWebpackPlugin = require("clean-webpack-plugin")
const vendorCSS = new ExtractTextPlugin('css/vendor.css')
const appCSS = new ExtractTextPlugin('css/app.css')
module.exports = function() {
  return {
    entry: {
      app: './main.js',
      vender: ['vue']
    },
    output: {
      filename: '[name].js',
      path: path.resolve(__dirname, 'dist')
    },
    resolve:{
        alias: {
            'vue$': 'vue/dist/vue.esm.js'
        },
        extensions: ['.js', '.vue']
    },
    module:{
        rules: [
            {
                test: /\.vue$/,
                exclude: /node_modules/,
                loader: 'vue-loader',
                options: {
                    loaders: {
                        css: appCSS.extract({
                            use: 'css-loader',
                            fallback: 'vue-style-loader'
                        })
                    }
                }
            },
            {
                test:/\.js$/,
                exclude: /node_modules/,
                loader: 'babel-loader'
            },
            {
          test: /\.(png|jpe?g|gif|svg)(\?.*)?$/,
          loader: 'url-loader',
          options: {
            limit: 10000,
            name: 'img/[name].[ext]'
          }
        },
            {
            test: /\.css$/,
            use: vendorCSS.extract({
                fallback: 'style-loader',
                use: ['css-loader', 'postcss-loader']
            })
            },
            
        ]
    },
    devtool: (process.env.NODE_ENV === 'production') ? '#source-map' : false,
    plugins: [
      new webpack.optimize.CommonsChunkPlugin({
        name: 'vendor',
        minChunks: Infinity
      }),
      new HtmlWebpackPlugin({
        filename: 'index.html',
        template: 'index.html',
        inject: true
      }),
      vendorCSS,
      appCSS
    ]
  }
}

if (process.env.NODE_ENV === 'development') {
    module.exports.devServer = {
      historyApiFallback: true,
      hot: true,
      inline: true
    }
    module.exports.plugins = (module.exports.plugins || []).concat([
      new webpack.HotModuleReplacementPlugin()
    ])
}

if (process.env.NODE_ENV === 'production') {
    module.exports.plugins = (module.exports.plugins || []).concat([
      new webpack.DefinePlugin({
        'process.env': {
            NODE_ENV: '"production"'
        }
      }),
      new webpack.optimize.UglifyJsPlugin({
        sourceMap: false,
        compress: {
            warnings: false
        }
      }),
      new webpack.LoaderOptionsPlugin({
        minimize: true
      }),
      new CleanWebpackPlugin(['dist'])
  ])
}

执行npm run dev命令后确实打开了localhost:8080，编译也没有错，但是很快出现以下界面，

下面是demo目录，我只是想编译app.vue，没有用到路由，想知道为什么直接连接异常。是配置的原因还是其他的原因。