System error

error:  Can't call method "get_tags" on an undefined value at /product/share/bookfinder/site/dir/i/index.mhtml line 562.
context: 
... 
558:  $link_tag_pages = 1;
559:  }
560: 
561:  $catalog_tags ||= new BookFinder::Catalog::Data::Tags;
562:  my $tag_list = $catalog_tags->get_tags($isbn);
563:  if ( $tag_list and @{$tag_list} ) {
564:  my $url = $ENV{BF_SITE_URL} . loc('/dir/t/');
565: 
566:  # may use for debugging:
... 
code stack:  /product/share/bookfinder/site/dir/i/index.mhtml:562
raw error






























Can't call method "get_tags" on an undefined value at /product/share/bookfinder/site/dir/i/index.mhtml line 562.


Trace begun at /usr/local/share/perl5/HTML/Mason/Exceptions.pm line 125
HTML::Mason::Exceptions::rethrow_exception('Can\'t call method "get_tags" on an undefined value at /product/share/bookfinder/site/dir/i/index.mhtml line 562.^J') called at /product/share/bookfinder/site/dir/i/index.mhtml line 562
HTML::Mason::Commands::__ANON__('BookFinder::Data::ISBN=HASH(0x557f6b731068)', 'Mobile Learning Anytime Everywhere A Book of Papers from MLEARN 2004', '') called at /product/share/bookfinder/site/dir/i/index.mhtml line 761
HTML::Mason::Commands::__ANON__('key', 'Mobile_Learning_Anytime_Everywhere-A_Book_of_Papers_from_MLEARN_2004/1845723449') called at /usr/local/share/perl5/HTML/Mason/Component.pm line 135
HTML::Mason::Component::run('HTML::Mason::Component::FileBased=HASH(0x557f75b71e48)', 'key', 'Mobile_Learning_Anytime_Everywhere-A_Book_of_Papers_from_MLEARN_2004/1845723449') called at /usr/local/share/perl5/HTML/Mason/Request.pm line 1297
eval {...} at /usr/local/share/perl5/HTML/Mason/Request.pm line 1292
HTML::Mason::Request::comp(undef, undef, undef, 'key', 'Mobile_Learning_Anytime_Everywhere-A_Book_of_Papers_from_MLEARN_2004/1845723449') called at /usr/local/share/perl5/HTML/Mason/Request.pm line 481
eval {...} at /usr/local/share/perl5/HTML/Mason/Request.pm line 481
eval {...} at /usr/local/share/perl5/HTML/Mason/Request.pm line 433
HTML::Mason::Request::exec('HTML::Mason::Request::ApacheHandler=HASH(0x557f75bd9688)') called at /usr/local/share/perl5/HTML/Mason/ApacheHandler.pm line 168
HTML::Mason::Request::ApacheHandler::exec('HTML::Mason::Request::ApacheHandler=HASH(0x557f75bd9688)') called at /usr/local/share/perl5/HTML/Mason/ApacheHandler.pm line 825
HTML::Mason::ApacheHandler::handle_request('HTML::Mason::ApacheHandler=HASH(0x557f72542f50)', 'Apache2::RequestRec=SCALAR(0x557f7614d330)') called at (eval 171) line 8
HTML::Mason::ApacheHandler::handler('HTML::Mason::ApacheHandler', 'Apache2::RequestRec=SCALAR(0x557f7614d330)') called at -e line 0
eval {...} at -e line 0