I have seen that crash, and it's something in CC. It's an internal object and nothing else could be affecting it without complicated reflection tricks specifically to get into CC nobody would ever have done. IIRC, I think I got it fixed but the fix is packaged with other changes that have bugs I haven't yet been able to stop.
Not in any way connected to the structure bug.
Gotcha. I'm not quite sure why I've been seeing it. It had disappeared entirely for quite a while and only recently started to appear again. It's weird.
Do you happen to remember what the crash that was posted a few pages back that had something to do with the structure mod not properly responding to modded blocks looked like? I'm suddenly very curious about that crash.