webpack版本4.6.0，extract-text-webpack-plugin的插件不能用了，用@next也不行，现在用mini-css-extract-plugin，还是报错

config.output.filename='[name].[chunkhash:8].js'

    config.module.rules.push({

        test:/\.styl/,

        use:[

            MiniCssExtractPlugin.loader,

            "css-loader",

            "postcss-loader",

            "stylus-loader"

        ]

    })

    config.plugins.push(

        new MiniCssExtractPlugin({

          // Options similar to the same options in webpackOptions.output

          // both options are optional

          filename: "[name].css",

          chunkFilename: "[id].css"

        })

    )

用的是命令： npm run prod