TypeError: Cannot read property '0' of null at toObjLatLng

[thijssmudde]

DraggablePolyline.onMapMouseMove contains a bug. When the parent goes from having a non-zero number of positions to zero, the component still fires the onMapMouseMove event.

{positions.length > 1
            ? <DraggablePolyline
                positions={positions}
                waypoints={waypoints}
                color={trackColor}
                opacity={trackOpacity.substr(0, trackOpacity.indexOf('%')) / 100}
                distanceMarkers={distanceMarkers}/>
            : null}