Potentially, there may be an extraneous catch case that can be removed.

Motivation:
Inside repairDatabase there is a try catch that catches a MustDowngrade Exception. The comment states "openDb can throw an exception with a MustDowngrade status if a collection does not have a UUID."

From a brief inspection, this seems to no longer be the case for openDB. Instead, it seem like repairCollections calls repairRecordStore which then calls _initCollection, where a MustDowngrade Error can occur.