_renderedChildren can get out of sync with DOM when render throws

[sophiebits]

ReactMultiChild doesn't properly handle errors that are thrown when rendering children; if one child throws then the other children being updated at the same time can have inconsistent values stored in _renderedChildren which can cause problems with future updates. It's unclear the best way to solve this.

[syranide]

The most straightforward solution would simply be to mark React as being in an unstable state and simply "shut it down". It would be deterministic at least :)

But it seems like being very surgical with some try/finally should be able to take care of most of the issues? (But you would want to keep that out of the hot code though, which you probably couldn't?)

[sophiebits]

It would be nice if one misbehaving component doesn't break the whole page. My guess is if we're careful about it we can make it happen. Not sure if any added try/finally calls would be a significant cost – hopefully not!

(Though in the general case where DOM manipulation can throw and can throw asynchronously (think web workers!), error recovery might not always be possible.)

[sophiebits]

Dupe of #2461.