Error was caused by chunks which didn't have a spawner (beaches/water)
still attempting to call the spawner.  The run_spawners was restructured
so that this wouldn't happen, but it means that the dungeons will be behave
similarly to the overworld when running spawners.  Also, there are about 7
closing braces in that function, and there's prolly a better way to do it.

I need to check to make sure that dungeons are still working properly.