Chartjs-Using chart.js in HotTowel , Angular.js

Depenedency injection have not done for your app.

 angular.module('app', ['chart.js']);

and also include chart.js file after app.js file in view.

also change .controller(controllerId, ['common', 'datacontext', dashboard])
to
.controller(controllerId, ['common', 'datacontext', 'dashboard'])