title: Error handling in RxJs combineLatest
body: <p>I am using rxJs to retrieve and store data across my app. 
  I have a scenario that I’m trying to subscribe to multiple observables using combineLatest. 
  The problem is that if some of the observables throws an error I am having trouble to subscribe since the subscribe function doesn’t fire. 
  I tried to add .catch(err => err) to the end of each single observable but then the combineLatest.subscribe doesn’t work. </p>