Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/49161
Avoid special strings, and default to null to mean undefined or unknown. This save us from bridging an unnecessary string but also makes the fallback name for logging network requests clearer.
Changelog: [Internal]
Reviewed By: bgirard
Differential Revision: D69058211
fbshipit-source-id: d83f424e0c2c23842554a8e4e616cad39719f311