I originally posted this crash report to the Tough Expansion github but it references an interface that mod doesn't use so they author suggested the problem might come from code in the main mod. I'm not sure exactly what is happening but here is a link to my original post on their github with two included crash reports. I'm hoping between you guys the problem will be easy to track down and fix.

p455w0rd/ToughExpansion#3 (comment)

Closing this issue here. The Tough Expansion author was able to track down the problem and says it should be fixed as soon as curse updates.