I think this is where trial and error comes into play. If GPT makes up a crate for, say, an HTTP server, and the API is very close to a real HTTP server, then it's not a big deal. You can just swap in a crate you know works.

If GPT is making up a crate and also mangling the use of such a crate, then it's probably not worth the human effort to fix all of that.

The same is true with any language: you'd have to try it a few times to decide if it's even worth the time saved.

Copilot is probably a better product for coding regardless, although I think it's deeply unethical and hope it gets sued out of existence.