sub check_name {
    my $name = $_[0];
    if ($name =~ /^[A-Z][A-Za-z\-']{2,40}/s) {
        return 1;
    } else {
        return "Friendly message...";
    }
}

##</code><code>##

# was $app{"first_name"} = ""; switch to next line
undef $app{"first_name"};