Summary:
## Description
When the TurboModule and the NativeModule systems are alive at the same time, after RN cleanup, if a TurboModule is required, we return `null` from TurboModuleManager. This causes `CatalystInstanceImpl.getNativeModule` to do a lookup on NativeModule registry, which throws an `AssertionError`, because the TurboModule isn't found. Instead of throwing an `AssertionError` from `CatalystInstanceImpl.getNativeModule`, this diff instead has that method return `null` in this particular case.
## Rationale
This should eliminate the crashes we're seeing in T46487253.
## Future action
In the future, we should guard `CatalystInstanceImpl.getNativeModule` with an `if (mDestroyed) return null;` statement. This'll ensure that if NativeModules are required after React Native has started cleanup, they'll be returned as `null`. Right now, we either return the destroyed NativeModule object, or create/initialize the NativeMoulde and return it, which is wrong.
Changelog:
[Android][Changed] - Make CatalystInstance.getNativeModule nullable
Reviewed By: JoshuaGross
Differential Revision: D21272029
fbshipit-source-id: 099ad9ab9fa2146299df4cf7f86ae7a8e526bb15