Crash while riding boats into the Void

The bug

When riding a boat or minecart, if you fall into the void, the game crashes, booting you back to the home screen.

While typically not an issue in general vanilla play, for mapmakers this may prove an issue if, for example, a player is tasked with riding a boat or minecart over an ice road and has to avoid falling off into the void.

Cause

It seems likely the error is caused by the boat/minecart entity being coded to simply despawn upon dropping below Y=0, and likely deleting any entities riding the boat at the time. However, since player entities cannot be "deleted", the game simply crashes.