To reproduce:
1. Import "Final IK" from the asset store
2. Open scene "Driving"
3. Include the scene in the build and build for WP8
4. Open up the solution with VS
5. Deploy in debug mode. A NullReferenceException is thrown, call stack points to line 146 in "IKMappingSpice.cs" (if (spine.Length != spineBones.Length) spine = new BoneMap[spineBones.Length];).

If you continue through the exceptions the project runs but with errors in console and the mannequin does not behave like it should

Running in the editor works fine.
This is a regression from 4.3.4f1 - everything worked fine there.