The endpoint /ontologies_full breaks when there is a data integrity issue in any submission

[mdorf]

The REST endpoint /ontologies_full returns Status 500 (Internal Server Error) when there is an integrity issue in one of the submissions it returns as part of its return value.

The case-in-point was the ontology AGRO submissionId 5, which had (as a result of a separate unrelated issue) its hasOntologyLanguage property set to NULL.

This endpoint should handle such issues gracefully without failing the entire request due to a single submission error.