If there is no error excerpt:

#!/usr/bin/perl

use strict;
use warnings;
use XML::Simple qw(:strict);

sub new {
    my ($class) = @_;

    #my ($proto) = @_;
    #to make the constructor both class and object method
    #my $class = ref($proto) || $proto;

    my $self = {

        #attributes of object
        _id                 => undef,
        _user_scenario      => undef,
        _result_type        => undef,
        _result_log_link    => undef,
        _not_exposed_reason => undef,
        _error_excerpt      => undef,
        _triage             => undef,
    };

    bless $self, $class;
    return $self;
}

sub error_excerpt { }
if ( defined('_error_excerpt') ) {
    print "error Excerpt\n";
}
else {
    if ( not defined('_error_excerpt') ) {
        print "No error Excerpt exists\n";
    }
}
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