Add 'use warnings' (or its equivalents) to all modules, or convince us that your favorite module is well-known enough and people can easily see the modules warn when something bad happens.

Error: WebService::MusicBrainz, WebService::MusicBrainz::Artist, WebService::MusicBrainz::Label, WebService::MusicBrainz::Query, WebService::MusicBrainz::Release, WebService::MusicBrainz::ReleaseGroup, WebService::MusicBrainz::Response, WebService::MusicBrainz::Response::Alias, WebService::MusicBrainz::Response::AliasList, WebService::MusicBrainz::Response::Artist, WebService::MusicBrainz::Response::ArtistList, WebService::MusicBrainz::Response::Disc, WebService::MusicBrainz::Response::DiscList, WebService::MusicBrainz::Response::ISRC, WebService::MusicBrainz::Response::ISRCList, WebService::MusicBrainz::Response::Label, WebService::MusicBrainz::Response::LabelList, WebService::MusicBrainz::Response::Metadata, WebService::MusicBrainz::Response::Puid, WebService::MusicBrainz::Response::PuidList, WebService::MusicBrainz::Response::Rating, WebService::MusicBrainz::Response::Relation, WebService::MusicBrainz::Response::RelationList, WebService::MusicBrainz::Response::Release, WebService::MusicBrainz::Response::ReleaseEvent, WebService::MusicBrainz::Response::ReleaseEventList, WebService::MusicBrainz::Response::ReleaseGroup, WebService::MusicBrainz::Response::ReleaseGroupList, WebService::MusicBrainz::Response::ReleaseList, WebService::MusicBrainz::Response::Tag, WebService::MusicBrainz::Response::TagList, WebService::MusicBrainz::Response::Track, WebService::MusicBrainz::Response::TrackList, WebService::MusicBrainz::Response::UserRating, WebService::MusicBrainz::Response::UserTag, WebService::MusicBrainz::Response::UserTagList, WebService::MusicBrainz::Track

This is not a critical issue. Currently mainly informative for the CPANTS authors. It might be removed later.