It's occasional, and triggered in a couple of other cases, but it seems a bit more prevalent when I'm playing on the Normandy map, with or without mods.

The panic dump is different every time, and it's usually one of the render threads that crashes while trying to execute setRenderPipelineState; I suspect it's happening at the wrong moment, like when something is exclusively locked, and the client is trying to update state between frames. I don't have access to the debug symbols that I could see in the AS client, so I couldn't really see when it's happening, this is mostly gut-feeling, other than I know it's setRenderPipelineState that's causing the crash.