这部分代码在报错，但找不到原因

  devServer: {
    before (app) {
      app.get('/api/seller', function (req, res) {
        res.json({
          errno: 0,
          data: seller
        })
      })
      app.get('/api/goods', function (req, res) {
        res.json({
          errno: 0,
          data: goods
        })
      })
      app.get('/api/ratings', function (req, res) {
        res.json({
          errno: 0,
          data: ratings
        })
      })
    },
    chainWebpack (config) {
      config.resolve.alias
        .set('components', resolve('src/components'))
        .set('common', resolve('src/common'))
    },
    baseUrl: ''
  }

报错信息如下：
ERROR ValidationError: webpack Dev Server Invalid Options

options should NOT have additional properties
options should NOT have additional properties

ValidationError: webpack Dev Server Invalid Options

options should NOT have additional properties
options should NOT have additional properties
at validateOptions (D:\vue\vue_sell_cube_4.0\node_modules\webpack-dev-server\node_modules\schema-utils\src\validateOptions.js:32:11)
at new Server (D:\vue\vue_sell_cube_4.0\node_modules\webpack-dev-server\lib\Server.js:57:5)
at serve (D:\vue\vue_sell_cube_4.0\node_modules@vue\cli-service\lib\commands\serve.js:165:20)
at processTicksAndRejections (internal/process/task_queues.js:93:5)

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! vue_sell_cube_4.0@0.1.0 serve: vue-cli-service serve
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the vue_sell_cube_4.0@0.1.0 serve script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\Lenovo\AppData\Roaming\npm-cache_logs\2020-04-15T20_39_30_177Z-debug.log