Conservative programming to avoid errors in update_swissindex_pharma

This should bring us a little bit further.

Cause of problem ist (as seen by bin/admin) a registration with a weird iksnr '274.0'
ch.oddb>  registration('274.0').name_base
-> Cardio-Pulmo-Rénal Sérocytol

I don't know where it comes from but it can be found inside AipsDownloads.xml by looking for '<authNrs>-</authNrs>'