javascript - vue项目执行npm run dev出现错误

使用vue-cli构建vue项目，在最后一步执行npm run dev时报错，报错如下，
$ npm run dev

sellapp@1.0.0 dev D:node6.2.0node_globaletcsellapp
node build/dev-server.js

module.js:442

throw err;
^

Error: Cannot find module 'webpack-merge'

at Function.Module._resolveFilename (module.js:440:15)
at Function.Module._load (module.js:388:25)
at Module.require (module.js:468:17)
at require (internal/module.js:20:19)
at Object.<anonymous> (D:\node6.2.0\node_global\etc\sellapp\config\dev.env.js:1:75)
at Module._compile (module.js:541:32)
at Object.Module._extensions..js (module.js:550:10)
at Module.load (module.js:458:32)
at tryModuleLoad (module.js:417:12)
at Function.Module._load (module.js:409:3)

npm ERR! Windows_NT 6.1.7601
npm ERR! argv "D:\node6.2.0\node.exe" "D:\node6.2.0\node_modules\npm\bin\npm-cli.js" "run" "dev"
npm ERR! node v6.2.0
npm ERR! npm v3.8.9
npm ERR! code ELIFECYCLE
npm ERR! sellapp@1.0.0 dev: node build/dev-server.js
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the sellapp@1.0.0 dev script 'node build/dev-server.js'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the sellapp package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! node build/dev-server.js
npm ERR! You can get information on how to open an issue for this project with:
npm ERR! npm bugs sellapp
npm ERR! Or if that isn't available, you can get their info via:
npm ERR! npm owner ls sellapp
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR! D:node6.2.0node_globaletcsellappnpm-debug.log
请问是哪里出问题呢？