uniapp 加载require('webpack')失败

uniapp项目里面增加vue.config.js文件

vue.config.js代码如下

const path = require('path')
const webpack = require('webpack')

module.exports = {

}

编译报错如下:
[HBuilder] 18:55:30.627 ERROR Error loading vue.config.js:
[HBuilder] 18:55:30.629 ERROR Error: Cannot find module 'webpack'
[HBuilder] 18:55:30.639 Error: Cannot find module 'webpack'
[HBuilder] 18:55:30.644 at Function.Module._resolveFilename (module.js:547:15)
[HBuilder] 18:55:30.646 at Function.Module._resolveFilename (D:\Works\HBuilderX\plugins\uniapp-cli\node_modules\module-alias\index.js:49:29)
[HBuilder] 18:55:30.660 at Function.Module._load (module.js:474:25)
[HBuilder] 18:55:30.661 at Module.require (module.js:596:17)
[HBuilder] 18:55:30.667 at require (internal/module.js:11:18)
[HBuilder] 18:55:30.668 at Object.<anonymous> (D:\My Documents\HBuilderProjects\demo3\vue.config.js:2:17)
[HBuilder] 18:55:30.675 at Module._compile (module.js:652:30)
[HBuilder] 18:55:30.677 at Object.Module._extensions..js (module.js:663:10)
[HBuilder] 18:55:30.682 at Module.load (module.js:565:32)
[HBuilder] 18:55:30.682 at tryModuleLoad (module.js:505:12)
[HBuilder] 18:55:30.688 at Function.Module._load (module.js:497:3)
[HBuilder] 18:55:30.688 at Module.require (module.js:596:17)
[HBuilder] 18:55:30.695 at require (internal/module.js:11:18)
[HBuilder] 18:55:30.696 at Service.loadUserOptions (D:\Works\HBuilderX\plugins\uniapp-cli\node_modules\@vue\cli-service\lib\Service.js:283:22)
[HBuilder] 18:55:30.705 at Service.init (D:\Works\HBuilderX\plugins\uniapp-cli\node_modules\@vue\cli-service\lib\Service.js:72:30)
[HBuilder] 18:55:30.706 at Service.run (D:\Works\HBuilderX\plugins\uniapp-cli\node_modules\@vue\cli-service\lib\Service.js:204:10)