pixi/rattler_network crashes without a useful error message if $HOME isn't defined

[mcbeth]

Checklist

• I added a descriptive title
• I searched open reports and couldn't find a duplicate

What happened?

If I try to access a private channel on Linux without the environment variable HOME set, pixi is crashing in
https://github.com/conda/rattler/blob/main/crates/rattler_networking/src/authentication_storage/backends/file.rs#L149

The error is just that "called 'Option::unwrap()' on a 'None' value"

I was debugging something else and had my whole environment empty, so that "HOME" was the problem wasn't immediately obvious. I don't have a problem with requiring that that environment variable being required, I just suspect it'd be better to catch that error and give a better message.

Additional Context

No response