# MAIN
unless ($result = my_sub() ) {
    # Now you use $result if it's not 0
}

# WRAPPER function
sub my_sub {
   eval { _my_sub(@_) };
   if ($@) {
      return $@;
   } else {
      return '';
   }
}

# Actual worker...
sub _my_sub {
# Do your stuff here. If something fails, do a die with a useful error message. Otherwise, return 0.

    # For example ...
    die "Bad data passed in.\n";
}