Handle malformed events in the DB

[Lan2u]

Noticed while testing that invalid events in the DB prevents us getting all events.

We should be ignoring invalid events

[erkannt]

How are invalid events getting into the database? Being robust against them sounds good but I feel our write side should prevent this.

[Lan2u]

In this specific case I was modifying an existing event type during local development.

More generally (academically / if I was deploying this at work) if we were to do rolling updates it is expected there will be events that older (but running) versions wouldn't know how to handle