错误：未捕获（在承诺中）：TypeError：无法在Angular2中读取null的属性'isSkipSelf'？

Question

我在调用mock.json

的http请求时遇到此异常

EXCEPTION: TypeError: Cannot read property 'isSkipSelf' of null
Error: Uncaught (in promise): TypeError: Cannot read property 'isSkipSelf' of null
    at resolvePromise (zone.js:538)
    at PromiseCompleter.reject (zone.js:515)
    at eval (core.umd.js:8981)
    at ZoneDelegate.invoke (zone.js:323)
    at Object.NgZoneImpl.inner.inner.fork.onInvoke (core.umd.js:6075)
    at ZoneDelegate.invoke (zone.js:322)
    at Zone.run (zone.js:216)
    at zone.js:571
    at ZoneDelegate.invokeTask (zone.js:356)
    at Object.NgZoneImpl.inner.inner.fork.onInvokeTask (core.umd.js:6066)