Fix crash in RCTExceptionManager (#54550)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/54550

# Summary

This diff resolves a crash in RCTExceptionManager by modifying error handling. It fixes the issue by checking if `RCTJSExtraDataKey` and `RCTJSStackTraceKey` are null or not in a dictionary initializer.

Also, `RCTJSExtraDataKey` is marked as nullable but its nullability is not checked.

## Changelog:
[iOS][Fixed] - A Crash when some error information are nil

Reviewed By: javache

Differential Revision: D87140823

fbshipit-source-id: 896d41c5f6559206a6515e402d2a503df6ddb63c