Any chance you had the editor running for a very long time before the error occurred? If so, I think @sven has mentioned something similar to this a couple of days ago.
I’m pretty sure it had been running for days. So if that could be what caused it, it probably is.
Also, as @sicher said above, the new editor is coming, not that I’ve had a ton of problems with this one. Just this issue, and a restart seems to have fix it.