安装webpack-dev-server后，npm run dev报错

> [email protected] dev F:\GitHub\vue\vueWebpack
> cross-env NODE_ENV=development webpack-dev-server --config webpack.config.js

F:\GitHub\vue\vueWebpack\node_modules\ajv-keywords\keywords\instanceof.js:52
throw new Error('invalid "instanceof" keyword value ' + c);
^

Error: invalid "instanceof" keyword value Promise
at getConstructor (F:\GitHub\vue\vueWebpack\node_modules\ajv-keywords\keywords\instanceof.js:52:11)
at Ajv.compile (F:\GitHub\vue\vueWebpack\node_modules\ajv-keywords\keywords\instanceof.js:21:27)
at Object.useCustomRule (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\compile\index.js:275:26)
at Object.generate_custom [as code] (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\dotjs\custom.js:32:24)
at Object.generate_validate [as validate] (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\dotjs\validate.js:347:35)
at Object.generate_anyOf [as code] (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\dotjs\anyOf.js:34:27)
at generate_validate (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\dotjs\validate.js:347:35)
at localCompile (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\compile\index.js:87:22)
at Ajv.compile (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\compile\index.js:56:13)
at Ajv._compile (F:\GitHub\vue\vueWebpack\node_modules\ajv\lib\ajv.js:358:27)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] dev: `cross-env NODE_ENV=development webpack-dev-server --config webpack.config.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] dev 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\Administrator\AppData\Roaming\npm-cache\_logs\2018-06-11T14_03_14_218Z-debug.log

解决：版本的影响