Sleeping in a bed while in a boat causes the player to get out of the boat, but not be transported to the bed until they get out of the bed. Instead, they appear to sleep to the side of the boat.

Steps to replicate

1. Ensure you are in the Overworld and it is either night or thundering
2. Place down a bed and a boat
3. Get in the boat
4. Sleep in the bed (ensure you are close enough)

Screenshot

I am unable to get a good camera angle of this bug in action in vanilla singleplayer; if you can see this bug occurring to other players on a multiplayer server, please comment on this bug report with an image of the bug in action.