Fixed on master with git:fafab77.
I was also unable to reproduce the mentioned issue in the mentioned way, but there was definitely a bug in getSnapshot(). Therefore, I'll change the ticket description to match a bug that we fixed. If the bug that @wginals could reproduce will be still reproducible, please open a new ticket.
Please also note that there must also be another bug somewhere because after editor is destroyed nothing should try to get snapshots. However, it would be very hard to make sure that it's always true, because short after editor is destroyed a lot may happen. Therefore, we chose the easier path to make sure that at least there's no error.