Possibly there may have been a small bug in one of the meshes? I am not too sure it had been a long time since I myself had made maps and experienced that issue. So I have forgotten how I would fix this issue, but I know I did a lot of trial and errors on trying to find a solution on my own. I know for sure one of my solutions was to get rid of all my downloaded objects. Then slowly put them back in little by little checking if my FH would still work after placing in each object. Once it finally crashed again I got rid of the culprit to make the game crash and continued on.
Not sure if this would help at all.