Can't call method "get_sections" on an undefined value

I ran this script and received this issue perhaps 1/5 times. Not sure how this gets caught.

Can't call method "get_sections" on an undefined value at /usr/local/share/perl/5.20.2/Wiktionary/Parser/Document.pm line 358.
    Wiktionary::Parser::Document::get_classifications(Wiktionary::Parser::Document=HASH(0x3a365b0), "class", "Wiktionary::Parser::Section::Synonym") called at /usr/local/share/perl/5.20.2/Wiktionary/Parser/Document.pm line 297

Sometimes Perl would cite this line as a problem:

Can't call method "get_synonyms" on an undefined value
my $synonyms = $document->get_synonyms();