My client still works and I haven't come across this in-game but I saw this while trouble shooting a different mod.
[STDERR/Sanguimancy]: [tombenpotter.sanguimancy.registry.PotionsRegistry:potionPreInit:31]: Severe error during potions pre-init, please report this to the mod author:
the whole log is here if you want it:
https://drive.google.com/file/d/0B_8hByLHUVnzdXFUc0xWVkVXeDg/view?usp=sharing