sub check_name {
    my $name = $_[0];
    if ($name =~ /^[A-Z][A-Za-z\-']+/s) {
        return 1;
    } else {
        return 0;
    }
}

unless (check_name($app{"first_name"}) {
    undef $app{"first_name"};
    push (@errors, "Helpful error message here...");
}