I kept getting crashes loading into worlds after I updated Soul Fire'd, so I naturally created an issue in their GitHub. They investigated the crash, figured out the cause, and told me that it has to be fixed on your side. They did offer a solution.
Crystal-Nest/soul-fire-d#54 (comment)

Mod Loader: Fabric 0.16.2
Mod List: Soul Fire'd 4.0.2, Cobweb 1.0.0, Forge Config API Port 4.2.11, Cloth Config 8.3.115, and VillagersPlus 1.9.2