Hi,
I couldn't replicate this but I made some changes to the mod that should hopefully fix this.
In the future when you report a bug please provide more information. The error message is good information but often it's not enough by itself. Give a short description of when this error occurred (loading game, loading save, during gameplay ...), what you were doing, does this happen consistently and so on. Things like game version, other mods installed, operating system etc. can also be very useful.
This applies to any mod or game error you report to any developer/modder. It makes it much easier to find and fix whats wrong. Thanks.