Missing perl error message

[dirkgr]

Fixes allenai/allennlp#5573.

[dirkgr]

There is now nothing left of this PR, but thanks to squash merging, GitHub can't figure this out automatically.

[Denbergvanthijs]

Thank you very much! Just a quick suggestion: wouldn't from shutil import which be a cleaner option instead of a try-except? It looks to be multiplatform and available since Python 3.3. When the executable is not found, it returns None.

[dirkgr]

While unlikely, that introduces a race condition. What if someone moves the perl executable after your call to which and before the call to subprocess.run?

[Denbergvanthijs]

That would indeed be a possibility, thank you for your answer!