Clarify error message in case no collectors are found for a file

[tobiasdiez]

In case no collector is found for a given file (e.g. if you run pytest something.unrecognized), then the somewhat cryptic error message

ERROR: not found: something.unrecognized
(no name 'something.unrecognized' in any of [])

With this PR, a more meaningful error message is displayed.

Not sure if such an almost-trivial change warrants an a changelog and authors entry.

[nicoddemus]

Thanks for the PR!

Not sure if such an almost-trivial change warrants an a changelog and authors entry.

I think so, improvements (however small) are worthy of note. 😁

Plus we need a test for the change, specially to ensure it doesn't regress. 👍

[tobiasdiez]

Thanks for the feedback. I've now added a changelog and authors entry, and fixed the tests.

[nicoddemus]

Looks great, thank you!

[Zac-HD]

@tobiasdiez - you'll need to merge in main in order to fix the jinja2 issue; then we should be ready to merge 🎉

[tobiasdiez]

Thanks, that worked like a charm!

[Zac-HD]

Thank you for the patch! Good error messages are enormously important to users, but so often neglected - it's a tricky form of "expert blindness" which makes contributions especially valuable 😍