Feature flag for `--debug` not working, maybe need to update docs

[adamreisnz]

• [x] I have tried upgrading by running bundle update vite_ruby.
• [x] I have read the troubleshooting section before opening an issue.

Description 📖

Looking at the documentation on debugging Vite:

• https://vite-ruby.netlify.app/guide/debugging.html
• https://vite.dev/guide/cli

The --debug flag is mentioned, and as per the Vite documentation it should be able to accept a feature identifier string, for example --debug hmr, to only debug output for that specific component, e.g.:

bin/vite dev --debug hmr

However, this doesn't work, as it interprets the parameter as something else and breaks the dev server altogether. Probably because the parameter isn't being passed by Vite Ruby to Vite itself?

So if we follow the Vite Ruby documentation, there is a second way to limit what gets logged, by using DEBUG env var, e.g. we can try:

DEBUG=vite:hmr bin/vite dev --debug

However, this also doesn't work as Vite seems to merge what is passed via the --debug flag with what's in DEBUG, and if you use both, it appears to ignore the env var value.

In the end you have to use only the env var:

DEBUG=vite:hmr bin/vite dev

And this behaves as expected. So basically you should not use the --debug flag, and instead only use the DEBUG env var if you want to limit the output that gets logged.

Not sure if this is a "bug" with the --debug flag perse (as it doesn't seem to pass the feature), or if documentation needs to be updated to clarify that you shouldn't use both --debug and DEBUG, and that passing features via --debug doesn't work.

Reproduction 🐞

1. Run bin/vite dev --debug hmr and observe that this doesn't work as expected – the HMR argument is instead used as base directory I believe.
2. Run DEBUG=vite:hmr bin/vite dev --debug and observe that this doesn't limit debugging to vite:hmr only, instead it logs everything.
3. Run DEBUG=vite:hmr bin/vite dev and observe that this works as expected