Crash after dispensing flint and steel downwards

It is possible to dispense fire downward in a way that immediately crashes the game and corrupt the world save in a way such that the crash repeats whenever the gamer attempts to load that world.

Steps to reproduce:

1. Place a dispenser facing down with an obsidian block next to the block it would dispense into and no block below that. (see attached screenshot)
2. Put a flint and steel into the dispenser.
3. Trigger the dispenser.

At this point the game will crash with:

The game crashed whilst exception while ticking
Error: java.lang.IllegalStateException: Unable to get CCW facing of down
Exit Code: 255

Attempting to load the world again will cause the same crash. Attempting to upgrade such a world (e.g. from 1.16.4 to 20w51a) will hang the game until it is forcibly closed, at which point the launcher also reports that error.

I attached crash logs from 1.16.4 and 20w51a, as well as a screenshot demonstrating the contraption to cause this crash.