I tested this with my mods and also without a single mod enabled (vanilla, so I put "Van" in the title though the title has limited characters). It happened for both cases, multiple times.
Error seems to happen only when pawns get lucky and make a sarcophagus that has art. All my other sarcophagi that didn't get art spawned in fine. But lots of completely wasted time & resources when I should be getting art - a good thing becomes a terrible thing, skilled constructors are punished.
Error seems to happen only when pawns get lucky and make a sarcophagus that has art. All my other sarcophagi that didn't get art spawned in fine. But lots of completely wasted time & resources when I should be getting art - a good thing becomes a terrible thing, skilled constructors are punished.