symbol-observable 404 (Not Found) (exemplo do blog)

[edneyreis999]

Quando tento iniciar a aplicação do capitulo 8 ( blog). A aplicação não sai do loading e printa esse erro no console.

zone.js:101 GET http://localhost:8080/symbol-observable 404 (Not Found)

Error: (SystemJS) XHR error (404 Not Found) loading http://localhost:8080/symbol-observable(…)(anonymous function) @ (index):13ZoneDelegate.invoke @ zone.js:323Zone.run @ zone.js:216(anonymous function) @ zone.js:571ZoneDelegate.invokeTask @ zone.js:356Zone.runTask @ zone.js:256drainMicroTaskQueue @ zone.js:474ZoneTask.invoke @ zone.js:426
zone.js:101 GET http://localhost:8080/symbol-observable 404 (Not Found)scheduleTask @ zone.js:101ZoneDelegate.scheduleTask @ zone.js:336Zone.scheduleMacroTask @ zone.js:273(anonymous function) @ zone.js:122send @ VM3090:3fetchTextFromURL @ system.src.js:1057(anonymous function) @ system.src.js:1778ZoneAwarePromise @ zone.js:584(anonymous function) @ system.src.js:1777(anonymous function) @ system.src.js:2806(anonymous function) @ system.src.js:3380(anonymous function) @ system.src.js:3692(anonymous function) @ system.src.js:4084(anonymous function) @ system.src.js:4547(anonymous function) @ system.src.js:4816(anonymous function) @ system.src.js:413ZoneDelegate.invoke @ zone.js:323Zone.run @ zone.js:216(anonymous function) @ zone.js:571ZoneDelegate.invokeTask @ zone.js:356Zone.runTask @ zone.js:256drainMicroTaskQueue @ zone.js:474ZoneTask.invoke @ zone.js:426

Será que alguém pode me dar uma força?