If a bat is resting on a block, and is scared by an approaching player it sometimes flies into the block above it.

To reproduce:

Create a 3x1x3 block platform. (Might need air on top)
Spawn a bat in the centre.
Approach the bat from the side or bellow (I doesn't always work if you come directly at it from the side.)

Expected behaviour: the bat flies away, but not into a block

Experienced behaviour: the bat flies into the block and takes damage.