Alright, so it sounds like your actor BrainrotBoxPvp.custom references BrainrotBoxPvp.TRALARERO, and your first actor is always loaded while your second actor is spatially loaded. This is incompatible because the first model can not be loaded without the second model also being loaded.
The easiest solution here is to turn off “is spatially loaded” on the actor BrainrotBoxPvp.TRALARERO
If the two actors are physically near each other, you could instead set the first actor to “is spatially loaded” and that should also clear up the error.