.style文件导致错误“路径必须是一个字符串。收到未定义”与UglifyJSPlugin --optimize-minimize

Question

我正在使用带有以下配置文件的webpack：

'use strict';

var webpack = require('webpack')
var ExtractTextPlugin = require('extract-text-webpack-plugin')
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');

module.exports = {
  entry: {
    'index': './index.js'
  },
  output: {
    filename: './dist/[name].min.js'
  },
  module: {
    loaders: [
      {
        test: /\.(jsx|js)$/,
        exclude: /node_modules/,
        loaders: 'babel-loader'
      },
      {
          test: /\.styl$/,
          loader: ExtractTextPlugin.extract('style-loader', 'css-loader!autoprefixer!stylus-loader')
      }
    ]
  },
  plugins: [
    new ExtractTextPlugin('./dist/[name].min.css'),
    new UglifyJSPlugin( {  minimize: true })
  ]
}

当我输入

  

webpack --config ./min.config.js

运行良好，我看到了.js文件的创建。但是当我输入

时

  

webpack --optimize-minimize --config ./min.config.js

我收到了以下错误：

ERROR in ./~/css-loader!./~/autoprefixer-loader!./~/stylus-loader!./index.styl
Module build failed: TypeError: /home/test/index.styl:3:1
   1| @import '~normalize.css/normalize.css'
   2| @import './style'
   3|
------^

Path must be a string. Received undefined

    at assertPath (path.js:7:11)
    at extname (path.js:1431:5)
    at new SourceMapper (/home/test/node_modules/stylus-loader/node_modules/stylus/lib/visitor/sourcemapper.js:41:7)
    at Renderer.render (/home/test/node_modules/stylus-loader/node_modules/stylus/lib/renderer.js:94:9)
    at /home/test/node_modules/stylus-loader/index.js:149:12
    at tryCatchReject (/home/test/node_modules/when/lib/makePromise.js:840:30)
    at runContinuation1 (/home/test/node_modules/when/lib/makePromise.js:799:4)
    at Fulfilled.when (/home/test/node_modules/when/lib/makePromise.js:590:4)
    at Pending.run (/home/test/node_modules/when/lib/makePromise.js:481:13)
    at Scheduler._drain (/home/test/node_modules/when/lib/Scheduler.js:62:19)
    at Scheduler.drain (/home/test/node_modules/when/lib/Scheduler.js:27:9)
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)
 @ ./index.styl 4:14-156

如何解决？