.+prenom Pywikibot script can fails with such a message:
Traceback (most recent call last): […] pywikibot.data.api.APIError: modification-failed: Item [Q7276690|Q7276690]] already has label "Diao" associated with language code de, using the same description text. CRITICAL: Waiting for 1 network thread(s) to finish. Press ctrl-c to abort
This APIError message is directly useful for the user, and so should be exposed.