This is the best place for me to leave this, so here's a bug report. On map 28, accessing the weapons wheel while the player is holding the artifact they have just grabbed results in this error:
If this is what I think this is(The weapon wheel not having an image to assign to something that the weapon wheel thinks is a weapon), this may not be strictly limited to that level.
To reproduce: Changelevel to MAP28, grab the first artifact, and while holding it press the key to open the weapon wheel.