Navigator: null check on gesture.overswipe to prevent crash

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`.

**Test plan (required)**

My team's app is using this change.

Adam Comella
Microsoft Corp.
Closes https://github.com/facebook/react-native/pull/11017

Differential Revision: D4207277

Pulled By: ericvicenti

fbshipit-source-id: a22817c2ebec1c996583269a59d6767f5713771b
This commit is contained in:
Adam Comella 2016-11-20 15:18:48 -08:00 committed by Facebook Github Bot
parent dcbcda75ec
commit 54e947152f

View File

@ -914,7 +914,7 @@ var Navigator = React.createClass({
}
return;
}
if (this._doesGestureOverswipe(this.state.activeGesture)) {
if (gesture.overswipe && this._doesGestureOverswipe(this.state.activeGesture)) {
var frictionConstant = gesture.overswipe.frictionConstant;
var frictionByDistance = gesture.overswipe.frictionByDistance;
var frictionRatio = 1 / ((frictionConstant) + (Math.abs(nextProgress) * frictionByDistance));