Summary:
Sometimes, `gesture.overswipe` can be `null`/`undefined` in `_moveAttachedGesture` resulting in a crash. This change adds a null check to avoid the crash. `_matchGestureAction` has a similar check so it looks like this case was overlooked in `_moveAttachedGesture`.
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Adam Comella
Microsoft Corp.
Closes https://github.com/facebook/react-native/pull/11017
Differential Revision: D4207277
Pulled By: ericvicenti
fbshipit-source-id: a22817c2ebec1c996583269a59d6767f5713771b
54e947152f