Serve "development" vs. "production" for packages that support it

[FredKSchott]

Some packages behave differently in development vs. production. Usually, this will be something like extra hooks needed for HMR (React), or better error messages (React, Vue, etc).

The abstract way to support this would be to pass something like ?env=NODE_ENV,development or ?env=NODE_ENV,producton. However, CJS packages would need to be re-built based on these values so it's not something that we can just flip on & off in a CJS world.

In an export maps world, we would still need to support two different builds since we'd resolve entries differently based on dev vs. prod.

For those reasons, we should probably support only NODE_ENV as an option for now, with two different builds for each package that behaves differently for dev vs. prod. Something like: ?env=development or ?dev.

[EpicHigh]

+1: I'm looking forward to this issue too.

[MarcDwyer]

I see this issue being opened back in January. Is there something stalling the ability to serve both React's dev build and production build? Not being able to use tools such as react-refresh sucks.