Perhaps, as other monks have mentioned, something along these lines might point you in the right direction.

#!/usr/bin/perl

use strict;
use warnings;

my $e = Error::Excerpt->new;

print $e->get_error_excerpt, qq{\n};

$e->set_error_excerpt(q{We have an error});

print $e->get_error_excerpt, qq{\n};


package Error::Excerpt;

sub new {
  my $class = shift;
  my $self = {
    _error_excerpt => undef,
  };
  bless ($self, $class);
  return $self;
} 

sub set_error_excerpt{
  my $self  = shift;
  my $ee    = shift;
  $self->{_error_excerpt} = $ee;
} 

sub get_error_excerpt{
  my $self  = shift;
  my $ee    = $self->{_error_excerpt};
  return $ee?$ee:q{No Error Excerpt};
}
[download]

No Error Excerpt
We have an error
[download]

imo, dividing up the task using getters and setters is often worth considering. Add error checking as appropriate.