Occluding the engine allows it to fire anyway

[MeltedHugo]

How to reproduce:
In the VAB, attach something like a tank (or any other part) to the back of an engine and disable the engine's fairing.

Result:
The engine fires and produces thrust.

Expected behavior:
The engine should either refuse to ignite if something is directly occluding the nozzle (KSP1 behavior iirc) or explode.

Example video footage (not by me):
https://youtube.com/clip/UgkxozY_PVoDdWC8I5qRzR9DXdmMhBS8l3rw

Edited February 26, 2023 by MeltedHugo
clarification of reproduction steps