Catch nulls in updatePosition and adjustForCaptureGestures (#150)
Catch nulls in updatePosition and adjustForCaptureGestures (#150)

On some calls to updatePosition this.drawer and this.main were null and
to adjustForCaptureGestures this.mainOverlay and this.drawerOverlay
were null.
This occurred on Android API Level 22 but not on 23 or earlier.

Signed-off-by: Ian Hilt <57a33a5496950fec8433e4dd83347673459dcdfc@novacreative.com>
jeffchienzabinet/react-native-drawer,root-two/react-native-drawer