Error while running 'ionic serve' command

When I run ‘ionic serve’ command within my app directory it produces the following error. So can anyone figure out where I am going wrong. Any help would be great.

sh: 1: ionic-app-scripts: not found
npm ERR! file sh
npm ERR! code ELIFECYCLE
npm ERR! errno ENOENT
npm ERR! syscall spawn
npm ERR! ionic-hello-world@0.0.0 ionic:serve: `ionic-app-scripts serve "--v2" "--address" "0.0.0.0" "--port" "8100" "--livereload-port" "35729"`
npm ERR! spawn ENOENT
npm ERR!
npm ERR! Failed at the ionic-hello-world@0.0.0 ionic:serve script 'ionic-app-scripts serve "--v2" "--address" "0.0.0.0" "--port" "8100" "--livereload-port" "35729"'.
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 ionic-hello-world package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     ionic-app-scripts serve "--v2" "--address" "0.0.0.0" "--port" "8100" "--livereload-port" "35729"
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs ionic-hello-world
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls ionic-hello-world
npm ERR! There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2017-04-26T07_50_44_054Z-debug.log
There was an error serving your Ionic application: There was an error with the spawned command: serve