The warn $error will issue this message if there is a message.
It's because how warn $blabla works : it does not work, you have to add ""
# errors thrown while loading installer data should be logged
if($error) {
warn "C4::Installer::load_sql returned the following errors while attempting to load $filename:\n";
# errors thrown while loading installer data should be logged
if($error) {
warn "C4::Installer::load_sql returned the following errors while attempting to load $filename:\n";