Fixes #367 bug related to undefined items/sorting contract

I fixed the bug and re-enabled the table sorting by most recent publication.

The bug ended up being caused by the fact that the Literature Service sometimes does not provide information for PMID queries, even though the publication does exist.

I check if the query returned info for a PMID, and if it did not, I splice the array and remove this result.

The previous code was raising the "Comparison method violates its general contract" error due to sorting with undefined items.

The current code removes these undefined items, and sorts by most recent year.