`canonicalizing path failed` does not show which path failed

[ppom0]

Hi! I switched several backups from restic to rustic, and I love it, many thanks!

Converting my last repository, which had a lot of backup path, I stumbled across this error:

canonicalizing path failed: `Os { code: 2, kind: NotFound, message: "No such file or directory" }`

It took me some research to find that this was one of the backup paths, at first I thought this was one of the globs that didn't match.

I think it would make it more explicit and user-friendly to show an error like this instead:

canonicalizing path /path/that/not/exists failed: `Os { code: 2, kind: NotFound, message: "No such file or directory" }`

What do you think? I can try doing it if you're ok with the proposal.

[ppom0]

Also restic quietly ignores inexistant paths. I like restic behavior, but I'd understand you prefer exiting with an error instead.