It's also running on very old hardware, potentially with some electrolytic capacitors that have dried up. And, there's always the possibility that it's a gamma ray [1]!
To me, that error message was caused by some panic, and then the OS began gracefully shutting down the application in this case DooM - which would not have been done by the program itself. Therefore I conclude it was the OS.
I am not an OS developer, so I take my own conclusion with a grain of salt.
Did you read the article? They specifically said it was a variable in the game engine code that causes the overflow. A program crashing causes the OS to show the error, but the bug that caused the crash was clearly in the game code itself.
Any OS this game engine ran on would experience this crash.
