webpack extract-text-webpack-plugin插件抽离css报错

Error: Chunk.entrypoints: Use Chunks.groupsIterable and filter by in

#原因：extract-text-webpack-plugin还不能支持webpack4.0.0以
上的版本。查看package.json中的版本信息

npm install --save-dev extract-text-webpack-plugin@next

#也可以用
npm insatll mini-css-extract-plugin --save
module: {
    rules: [
     {
                test: /\.css$/,
                use: [
                {
                        loader: MiniCssExtractPlugin.loader,

                    },
                   'css-loader'
                ]
            },
    ]
  },
 plugins: [
   new MiniCssExtractPlugin({
    filename:'[name].css',
   })
]