Flakes: Enhance Error when Files are not Added to Git

[Malix-Labs]

Problem

Currently, about flakes development, the error when files are not added to git are not that helpful

Proposed Solution

Would be nice if nix inspected the source tree and if an untracked file did exist there, that it would give you a more helpful error to run git add -- <file>

Priorities

Add 👍 to issues you find important.

[hraban]

It would be nice if this functionality included support for the flake.nix file itself

[edolstra]

Duplicate of #4507

[Malix-Labs]

thanks @edolstra !

By the way, if you edit your comment by making its content only strictly be "Duplicate of #ID", it will be marked as duplicate

[edolstra]

@Malix-off Thanks for letting me know!

[hraban]

We're at risk of losing the 43 👍 votes for this issue if it just gets closed and marked as dupe without consolidating those, somehow. Don't know how much that matters but since the issue template explicitly asks for it, it might be at least somewhat relevant.

[Malix-Labs]

Indeed, the upvote differential is quite significant