Backport of Fix for ENSCORESW-2340 (handling NULL translation versions)

Created by: tgrego

Description

This is a backport of https://github.com/Ensembl/ensembl/pull/242

Use case

Check original PR

Benefits

Have this fix on release/93

Possible Drawbacks

If applicable, describe any possible undesirable consequence of the changes.

Testing

Have you added/modified unit tests to test the changes?

If so, do the tests pass/fail?

Have you run the entire test suite and no regression was detected?