Fix the bug that 'flatMap' swallows OnErrorNotImplementedException

[zsxwing]

Fixed #1365
Not sure if any other place will swallow OnErrorNotImplementedException or the fatal errors.

[cloudbees-pull-request-builder]

RxJava-pull-requests #1292 SUCCESS
This pull request looks good

[cloudbees-pull-request-builder]

RxJava-pull-requests #1293 SUCCESS
This pull request looks good

[mofleury]

Hi all,

I'm new here, so I may be missing something, but I'm afraid that this issue should not be closed just yet.

Indeed, it looks like there is still a problem if there is more than one flatMap in the chain.

Here is a unit test to reproduce the bug (I used the previous unit test that was added as part of this bugfix, and simply added an additional flatMap stage) :

    @Test(expected = OnErrorNotImplementedException.class)
    public void testSubscribeWithoutOnError() {
        Observable.just("a", "b")
        .flatMap(s -> Observable.just(s + "1", s + "2"))
        .flatMap(s -> Observable.error(new Exception("test")))
        .forEach(System.out::println);
    }

The output I get is nothing, and no error either.

Should I submit a new issue, or can you reopen this one?

Thanks!

[rekhajoshm]

Think the issue still exists, there needs to be clear functionality by which exception can be cleanly trapped and rethrown if needed(user preference) to upper layers.thanks