handle react-native resolver

[hosseinmd]

Specially in react-native repack, we need to resolve from source code

[TkDodo]

I have never seen a top-level react-native field in package.json, and a quick google search also didn't yield any good results. Can you please elaborate what this does, which bundlers interpret this field and why we need it? Thanks.

[hosseinmd]

Look at these libraries:
React-navigation
React-freeze
react-native-video
react-native-gesture-handler
cross-fetch
lottie-react-native

And so many libraries which wanna work with platform specific files ('.native.ts' or '.android.ts') should be considered this.
Without specifying source for react-native loaders for handling tree shaking will load module and then import react-dom in react-native

[hosseinmd]

This is repack mainFields priority
https://github.com/callstack/repack/blob/6a210ed2559bbef2468c27f517d2eaaba2510a87/packages/repack/src/utils/getResolveOptions.ts#L111