Make errors during remove source a warning rather than a hard error

[mfazekas]

Fixes/silences the following error:

java.lang.Error: Cannot remove detached source
    at com.mapbox.mapboxsdk.maps.NativeMapView.nativeRemoveSource(NativeMapView.java)
    at com.mapbox.mapboxsdk.maps.NativeMapView.removeSource(NativeMapView.java:925)
    at com.mapbox.mapboxsdk.maps.Style.removeSource(Style.java:175)
    at com.mapbox.rctmgl.components.styles.sources.RCTSource.removeFromMap(RCTSource.java:158)
    at com.mapbox.rctmgl.components.mapview.RCTMGLMapView.removeAllSourcesFromMap(RCTMGLMapView.java:1229)
    at com.mapbox.rctmgl.components.mapview.RCTMGLMapView.setReactStyleURL(RCTMGLMapView.java:755)
    at com.mapbox.rctmgl.components.mapview.RCTMGLMapViewManager.setStyleURL(RCTMGLMapViewManager.java:120)
    at java.lang.reflect.Method.invoke(Method.java)

I could not reproduce the root cause, either a race, or because the sources were removed twice, somehow.
In any case the errors during source remove is now a warning only.

[ferdicus]

👍🏿