Doom 3 (Perfected Mod): Central Processing

While attempting to do an 'unscathed' type video for this whole level on nightmare difficulty, something very strange happened. While I kill everything before the boss without a scratch, I was prepared to accept how unlikely it is to avoid the constant damage of the BFG projectiles and just upload that. But instead of just killing the boss like normal, when I try to use the soul cube, some sort of glitch occurs where a blue horned demon spawns several feet off the ground and starts swatting at the boss, who dies shortly after. Then the game crashes before I can get a good look at the interloper. It doesn't look like an enemy that appears normally in the game, so it's probably a bug in the mod. EDIT: According to the mod creator, alt fire for the soul cube summons a "soul knight" that is hostile to enemies. Why the game crashed is still unknown.