Subscribe() suppresses errors

[mattcodez]

Server: 1.0.2
Client: Whatever that server version sends

So, I was having a recurring error in a subscribe() callback but had no way of knowing. Even adding an error callback does nothing. Some trimmed code from my application:

hz.currentUser().fetch().subscribe(user => {
      console.log('hi');
      throw 'test';
      console.log('foo');
    }, err => console.error(err), ()=>console.log('done!'));

Results in 'hi' being logged in the console but nothing else and no errors being thrown in Chrome 50. Note, code is being eval()'ed after a Babel transpile.

[danielmewes]

Note that subscribe is a method from RxJS: http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-subscribe

Their documentation doesn't seem to specify how exceptions thrown in one of the callbacks are handled, so I'm not sure if this is intended behavior from their side or not.

[marshall007]

@mattcodez see ReactiveX/rxjs#1135. Errors thrown in the next callback are not propagated to the subscription's error handler. As an alternative, you can use .forEach which returns a Promise and is rejected when any error is thrown on the subscription or in the next callback.

hz.currentUser().fetch().forEach(user => {
  console.log('hi');
  throw 'test';
  console.log('foo');
})
.catch(err => console.error(err))
.then(() => console.log('done!'))

If you prefer a solution that only uses Observables, you can use the .do() operator in place of the next handler:

hz.currentUser().fetch().do(user => {
  console.log('hi');
  throw 'test';
  console.log('foo');
})
.subscribe(null, err => console.error(err), () => console.log('done!'))