There are multiple tools available to help you debug your app. This document will point to up-to date community guides of our preferred tools work and how to use them.
Reactotron is an open source tool that allows you to inspect every aspect of your React and React Native app. You can use it to debug your app, monitor network requests, and view your app's state and logs.
You can download it from the official releases from their github OS repo.
It is already setup to work with eigen, so you don't need to do anything else - if you face any issues post your questions on #practice-mobile channel.
In order to access the debugger you should open react native devtools (via artsy dev menu) and click on Open DevTools. From there you also have access to react dev tools and the new react native debugger.