Fix: remove server.browser.js in favor of export mapping to server

[lfre]

The browser subpath is for browser/client bundles. The server.browser path from Next.js is requested in Node.

Adding the corresponding export mapping to the same server file addresses the issue in Next.js 12.1.6.

[lfre]

@JoviDeCroock I'd appreciate it if you can take a look at this. The current server.browser.js file/reference does not fix the issue in Next 12.1.6.

[JoviDeCroock]

This looks wrong 😅 you both remove the contents of the file as well as introduce a new mapping. Next should not take browser for a node environment.

Also that file has no side-effects and no browser-specific behavior so should not cause issues, this might be a next issue instead

[lfre]

@JoviDeCroock I'm not following what you meant. There's no need for an additional file since the expectations from the server.browser.js are the same exports as server, so the mapping is all it's needed. Next 12.1.6 is requesting the file in Node, not through webpack, meaning the browser subpath will not match, and not find the current server.browser.js file.

This behavior was masked by this merged PR in Next vercel/next.js#36749, but the issue remains that if you do a require('react-dom/server.browser'). It will throw an error.

[JoviDeCroock]

but why would they use require('server.browser') that's just wrong 😅 we have export-maps now - i.e. what's happening here is a bit counterintuitive from what is expected.

EDIT: I mean I get why this fixes the problem but it makes me feel like we are fighting the intended usage

[lfre]

@JoviDeCroock Export maps are behaving as expected, though. The browser field will not clear in Node, and the path would have to be server not server.browser. I don't think there's a current expectation to load that file in the browser, if that's the case, then a browser field would need to get added to server.browser mapping.

[JoviDeCroock]

Heh, I honestly really don't like this but if they intend to use it that way this is mainly used for next either way 🤷‍♂️