I know what perlcritic is and that it is not a set of ironclad commandments or a set of strict rules that you must comply with.

My point was more to do with the perlcritic description of the problem than how to work around it, or document the way the real sub I was using did. I had felt it was too strongly pointing you in one direction that may not be right for you but on reading it again noting your bolded emphasis I suppose it is targeted to using undef for error reporting which my example was not doing.