We have seen occasional timeouts when indexing elasticsearch, these cause the indexing to stop and fail.

We should handle the response as the code indicates:
102 sub update_index {
103     my ($self, $biblionums, $records) = @_;
104 
105     my $conf = $self->get_elasticsearch_params();
106     my $elasticsearch = $self->get_elasticsearch();
107     my $documents = $self->marc_records_to_documents($records);
108     my @body;
109 
110     for (my $i=0; $i < scalar @$biblionums; $i++) {
111         my $id = $biblionums->[$i];
112         my $document = $documents->[$i];
113         push @body, {
114             index => {
115                 _id => $id
116             }
117         };
118         push @body, $document;
119     }
120     if (@body) {
121         my $response = $elasticsearch->bulk(
122             index => $conf->{index_name},
123             type => 'data', # is just hard coded in Indexer.pm?
124             body => \@body
125         );
126     }
127     # TODO: handle response
128     return 1;
129 }