Is this a bug?

gistfile1.txt

Rx.Observable.fromArray([1, 2, 3])
    .concat(Rx.Observable.throwException("woah nellie!"))
    .retry(3)
    .onErrorResumeNext()
    .subscribe(
        function (next) {
            console.log(next);
        });
1
2
3
1
2
3
1
2
3
TypeError: Cannot call method 'subscribe' of undefined