The latest unstable RimWorld build has a new drug stat system (in vanilla), due to be shipped as stable soon. The current version of Drug Stats doesn't work because the hook it uses has moved to a different place. In the meantime, you can remove the mod and use the vanilla system. It doesn't quite have as much stats, but it has the important ones, and will likely improve as Ludeon posts more updates.

I'm still pondering whether to retire this mod or hook into the new system.