error on adonis with electron

[ghost]

Uncaught Exception:
Error: listen EADDRINUSE 127.0.0.1:8000
at Server.setupListenHandle [as _listen2] (net.js:1330:14)
at listenInCluster (net.js:1378:12)
at GetAddrInfoReqWrap.doListen [as callback] (net.js:1492:7)
at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:55:10)

[ghost]

HTTPS: https://gitlab.com/somkundu1989/adonis-electron.git
SSH: git@gitlab.com:somkundu1989/adonis-electron.git

Error:: Output window opening still error appears.

$ npm start

electron-quick-start@1.0.0 start /data/html/electron-quick-start
electron .

info: serving app on http://localhost:8000
A JavaScript error occurred in the main process
Uncaught Exception:
Error: listen EADDRINUSE 127.0.0.1:8000
at Server.setupListenHandle [as _listen2] (net.js:1330:14)
at listenInCluster (net.js:1378:12)
at GetAddrInfoReqWrap.doListen [as callback] (net.js:1492:7)
at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:55:10)