CRITICAL: Can't start the dev server on Node 20 — flowtype ESLint plugin error #3565

Hey everyone,

I ran into an issue while setting up the project locally and wanted to
flag it as it would affect anyone trying to contribute on Node 20.

When I ran pnpm start, the dev server failed immediately with this error:

Failed to load plugin 'flowtype' declared in 'BaseConfig':
Package subpath './lib/rules/no-unused-expressions' is not defined
by "exports" in eslint-plugin-flowtype

After some digging I found that eslint-config-react-app has a dependency
on eslint-plugin-flowtype which doesn't play nicely with the version of
ESLint being used here when running on Node 20.

Node 20 is the current LTS version so this would affect a lot of people
trying to contribute for the first time.

I've put together a fix in PR #3557 if anyone wants to take a look. It's
a small override that resolves the conflict and gets the dev server running
without affecting any functionality.

My environment:

• Node: v20.20.2
• pnpm: v10.30.3
• OS: macOS (Apple Silicon / arm64)

Happy to provide any more info if needed!