OnErrorFlatMap & FlatMap

[benjchristensen]

Allow onError to be treated as a non-terminal event when flowing through flatMap/merge/SerializedObserver so onErrorFlatMap can be used.

[benjchristensen]

@spodila Does this fix the issue you reported to me?

[cloudbees-pull-request-builder]

RxJava-pull-requests #1395 SUCCESS
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[spodila]

@benjchristensen That should work, thanks.

[benjchristensen]

@headinthebox I'd like you to weigh in on this as I'm concerned with this.

It started out innocently ... but I find this onErrorFlatMap operator veers "outside the lines" as its purpose is basically to break the Rx contract be swallowing errors.

Really what's trying to be done here is map.onErrorResumeNext.merge, but flatMap is map.merge so errors get merged through and then are trying to be handled in a way that doesn't shut down a stream.

The general use case for onErrorFlatMap is to swallow errors so pipelines can be used as an event bus and errors don't act as terminal events.

I'd like to discuss this further before we ship 1.0. We may want a different solution than this one.

[benjchristensen]

Merged along with mergeDelayError changes in #1457