Suffocating in a piston

You can walk into an extended piston and suffocate in the piston

What I expected to happen was...:
Just walking towards the piston arm (I actually wanted to place blocks above originally)

What actually happened was...:
Walking towards the piston block while touching the piston arm made me suffocate

Steps to Reproduce:
1 - Put two pistons facing the same horizontal way and extend them
2 - Walk in the little space near the piston arm
3 - Walk in the piston block, suffocate, and die

(I only tried with sticky pistons but I assume it's the same with normal pistons)