I've heard this for 3 and 1/2 years that this can happen but I've never actually seen a documented case of this happening.
Discussion
I thought the protocol was supposed to deal with that otherwise no one would use it
It's why we use watchtowers, to watch the funds in our channels when our node is offline so that a channel partner doesn't push an incorrect channel state and the to force close the channel on us. But not everyone runs a watchtower. Most people don't I'd wager.