Description of problem:
Invoking to_string has the side effect of appending 'undef' to an array attribute.

Version-Release number of selected component (if applicable):
perl-Exception-Base-0.2500-1.el7.noarch.rpm
perl v5.16.3

How reproducible:
Always

Steps to Reproduce:
Can reproduce with this perl script:

#!/bin/perl
use warnings;
use strict;

use Data::Dumper;

use Exception::Base
    'MyException', => {
        message => 'Validation error',
        has     => [ qw(class errors) ],

        string_attributes => [ 'message', 'class', 'errors' ]
    };
eval {
    MyException->throw(
            class  => __PACKAGE__,
            errors => ["error 1", "error 2", "error 3"]
        );
};

my $exception = $@;

print( Dumper($exception->errors()) . "\n");

$exception->to_string();

print( Dumper($exception->errors()) . "\n");


Actual results:
Can see an additional 'undef' in the array returned after invoking to_string();

Expected results:
The returned array should be the same as when thrown.


Additional info: