Solving the Unhandled Promise Rejection Error in React Native with WebRTC

Discover how to fix the `TypeError: null is not an object` error in your React Native WebRTC application, focusing on permissions and calling functions.
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Understanding the Unhandled Promise Rejection Error in React Native

The Root of the Problem

The error you’re seeing seems to be associated with permission handling, specifically in the call screen of your WebRTC application. React Native needs certain permissions to access hardware features like the camera and microphone. When these permissions are not correctly handled or are set incorrectly, it leads to the runtime error you’re experiencing.

The stack trace reveals that the application is attempting to access an uninitialized object, likely indicating the absence of required permissions or misconfiguration of dependencies associated with InCallManager and WebRTCModules.

Step-by-Step Solution

Here’s how to resolve this error systematically. Below are the key adjustments you can make in your React Native code, particularly focusing on the permissions check and its utilization.

1. Permissions Handling

Ensure that you import the correct permissions package and use the appropriate methods to request camera permissions. In your permissionCheck function, replace the current implementation as follows:

[[See Video to Reveal this Text or Code Snippet]]

This adjustment ensures that the application asks for both camera and audio permissions from the user when starting the call.

2. Check Dependencies

Make sure your dependencies are correctly installed and linked. Occasionally, errors arise from improperly linked modules. Here’s what you should do:

Check that react-native-webrtc and react-native-incall-manager are correctly installed. Use commands like:

[[See Video to Reveal this Text or Code Snippet]]

If using React Native CLI, be sure to run:

[[See Video to Reveal this Text or Code Snippet]]

For those using Expo, ensure you use compatible versions of the above modules as Expo can have restrictions on certain native modules.

3. Rebuild the Project

After making any changes to the dependencies or permission handling, it’s a good practice to stop the React Native server and restart your project to build the native modules again.

[[See Video to Reveal this Text or Code Snippet]]

Then, for iOS or Android, run:

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or

[[See Video to Reveal this Text or Code Snippet]]

4. Handling State Updates Properly

The warning message in your stack trace regarding "Can't perform a React state update on an unmounted component" suggests that state updates are being attempted after the component’s lifecycle has ended. To resolve this, ensure that you correctly clean up any active subscriptions or asynchronous tasks in your useEffect cleanup function.

[[See Video to Reveal this Text or Code Snippet]]

Bear in mind that this ensures your component remains performant and maintains a clean state.

Conclusion

By implementing these changes, you should significantly mitigate the error messages you are encountering. Proper handling of permissions paired with thorough dependency management is key for any video calling features in a React Native application using WebRTC. Testing your application after each change can help capture and address any new issues early on. Happy coding!