The part that led me down this direction is a desire to use turfjs, along with react-native-maps to do some simple spatial analysis kinds of things.
However, turfjs depends on jsts which seems to depend on babel.js' ES2015, and some sort of presets associated with that.
In the searching I've been doing, it seems to be the case that babel creates a set of assumptions (reflected through presets?) that do not carry over into react-native, and jsts needs builds on top of babel. When you include the babel-preset-es2015 settings, there seems to be some sort of override of the typeof() function that doesn't translate into react-native properly.
npm install
To see the first stage bug, run this like you would any other react-native application.
react-native run-ios
or
react-native run-android
To see the second order bug (which may be the root cause), first install babel-preset-es2015
npm install babel-preset-es2015
then run it like you would any other react-native application (see above).