Marker-cluster error when toggling layers

[con...@mapfact.com]

Hi all,

I have a lot of markers on the same position and am using marker-clusters to indicate/give access to overlapping markers by means spiderfying.

http://s3.mapfact.com/society/all-nobel-prize-laureates/nobel.html 

Problem: When markers in a cluster are spiderfied and I choose another category in the layer control, I get this error: "Cannot set property '_leaflet_pos' of null".

Anyone ideas how to solve this? 

I have tried to unspiderfy the cluster when choosing another layer, but I can't figure out how to do it.

Cheers