React Native App Bug Fixing & Enhancement

I'm looking for an experienced React Native developer to help me fix bugs and issues in my existing application. In addition to troubleshooting and maintaining the current functionality, I want to add a user authentication feature to the app.

Ideal skills for this job include:
- Proficiency in React Native
- Experience with debugging and troubleshooting mobile applications
- Knowledge of implementing user authentication

Please note, the user authentication will solely be an email and password system.