If you are going to put settings into a Perl module, be sure that this module includes use strict and use warnings, and that it is either used or required by “the main settings-handling module” of your application.

“Incorrect or incomplete settings” are a very troublesome source of application problems for many end-users, and the time you spend aggressively checking them for omissions and inconsistencies (producing meaningful messages to describe each case) will be well worth the time.