I figured out what was causing the CTDs. The leash blocking promotion (in unmodded RiFE) requires leash4 and also removes all leash tags when acquired. In the module I added the bMustMaintain tag to the leash blocking promotion. So the requirement is met, the leash blocking promotion is acquired, the leash promotion is removed, and the requirements are then no longer met. Rather than removing the leash blocking promotion, Civ just decides to crash instead.
The first post contains a new version of the module.