How to import perl module (xml::twig) in a dancer framework

Question

I am working on a webapp using Perl Dancer Framework. I am using XML::Twig in lib/myapp.pm file but it seems to be causing a problem for me:

package map;
use Dancer ':syntax';

use LWP::Simple;
use XML::Twig;

our $VERSION = '0.1';

get '/' => sub {
    template 'index';
};

post '/' => sub {

    my $id = params -> {id};
    my $ls = params -> {list};

    my @as = split /\,/, $ls;

    foreach my $a (@as){

        #assemble the epost URL
        my $db = 'gene';
        my $base = 'http://eutils.ncbi.nlm.nih.gov/entrez/eutils/';
        my $url = $base . "esummary.fcgi?db=$db&id=$a";
        my $docsums = get($url);

        #parse the record
            my $t= XML::Twig->new(twig_roots => { 
              'DocumentSummary' => \&summary
             });
            $t->parse($docsums);

        }
    };

    true;

The error it gives is:

Runtime Error runtime error Can't use an undefined value as a HASH reference at /Library/Perl/5.18/Dancer/Route/Registry.pm line 125