clarify error message on missing path

[H4vC]

fix for #4277

[H4vC]

This is a trivial change.

[davidhewitt]

Thanks for the PR! We actually have #4043 also improving this line, but that got stuck in review limbo. Would you be willing to help finish that one off instead please? You could pull those commits and add some extra ones on top.

The changes waiting on that PR were:

• how to test it - just write a unit test that attempts to read from a nonexistent file at the bottom of the same file
• some suggestions to actually include PYO3_CROSS_LIB_DIR in the error message

[mrexodia]

Thanks for the PR! We actually have #4043 also improving this line, but that got stuck in review limbo. Would you be willing to help finish that one off instead please? You could pull those commits and add some extra ones on top.

The changes waiting on that PR were:

• how to test it - just write a unit test that attempts to read from a nonexistent file at the bottom of the same file
• some suggestions to actually include PYO3_CROSS_LIB_DIR in the error message

This change as-is would have saved me a lot of time already. Considering it's a 1-line change wouldn't it be good to merge this as-is and then refactor later?

[davidhewitt]

I completely agree and am sorry that this wasn't fixed sooner. Nobody wants time wasted by bad error messages.

I found a moment to push to #4043 just now, so let's merge that one. Thank you both for reminding me that this error message matters. (You were not the first folks to hit this case.)

[mrexodia]

Awesome, thanks for the quick fix!