Unhandled Promise rejection error angular 2 using angular cli -

hi working on tutorial provided @ link -

http://angular.io/docs/ts/latest/tutorial

with changes done http part of tutorial following error :

unhandled promise rejection: "patchproperty/desc.set/wrapfn@http://localhost:4200/vendor/zone.js/dist/zone.js:769:27 zonehttp://localhost:4200/vendor/zone.js/dist/zone.js:356:24 zonehttp://localhost:4200/vendor/zone.js/dist/zone.js:256:29 zonetask/this.invoke@http://localhost:4200/vendor/zone.js/dist/zone.js:423:29

error loading http://localhost:4200/main" ; zone: ; task: promise.then ; value: error: patchproperty/desc.set/wrapfn@http://localhost:4200/vendor/zone.js/dist/zone.js:769:27 zonehttp://localhost:4200/vendor/zone.js/dist/zone.js:356:24 zonehttp://localhost:4200/vendor/zone.js/dist/zone.js:256:29 zonetask/this.invoke@http://localhost:4200/vendor/zone.js/dist/zone.js:423:29

error loading http://localhost:4200/main

the question how fix above error