I was observing cases where builtEvents[modificationIndex] was not
having the same eventId as the udpatedEntity in handleDatabaseChangeSet.
In particular, I observed both cases that
- there was no item in the list yet with the same eventId as the updated
one
- there was an item with the same eventId already in the list, but at a
different position.
Whenever this happened, the timeline would render missing, duplicated,
or swapped messages in the timeline.
Instead of relying on the modificationIndex to be the same for both the
change set and builtEvents, look up the proper index by eventId.
