Issue when running without _mockLocations.js

I got issue as below when comment out the _mockLocations.js, and fake with gps on android or running on real iPhone device!
![picturemessage_a2desict umw](https://user-images.githubusercontent.com/19544290/82813634-9ee56f80-9ebf-11ea-9ff8-db43cb0da15f.png)

My github repo for this project: https://github.com/GinnyMorning/track010

Can you check why I got this issue,
Thank you.