ScorpiouprisingCheck to make sure you don't have a brush with a light texture on it stuck inside of some geometry. Or a prop that is stuck inside a brush. I've had that happen before and that tends to be the culprit. Turn off props and compile to see if that resolves the issue, if so that's probably what is causing it.
I've narrowed the problem area down to around 50 brushes (arches and cylinders in the lighthouses), and neither of those issues that you said are what's causing my error- I've already checked. I'll go through it again tomorrow.