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_globaletcsellappnode build/dev-server.js
module.js:442
12throw err;^Error: Cannot find module 'webpack-merge'
12345678910at 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. (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 6.1.7601npm ERR! argv "D:\node6.2.0\node.exe" "D:\node6.2.0\node_modules\npm\bin\npm-cli.js" "run" "dev"npm ERR! node v6.2.0npm ERR! npm v3.8.9npm ERR! code ELIFECYCLEnpm ERR! sellapp@1.0.0 dev:
1node build/dev-server.jsnpm ERR! Exit status 1npm 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.jsnpm ERR! You can get information on how to open an issue for this project with:npm ERR! npm bugs sellappnpm ERR! Or if that isn't available, you can get their info via:npm ERR! npm owner ls sellappnpm 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？