Not sure how it happened, but I've got this error since 7.1:

801x oUF_Phanx\Functions.lua:211: Usage: UnitHealth("unit") [C]:: ? oUF_Phanx\Functions.lua:211: in function <oUF_Phanx\Functions.lua:206> (tail call): ? oUF\events.lua:48: in function <oUF\events.lua:46> (tail call): ?

This was already fixed in 0edf16c, and a release will be tagged as soon as I've had a chance to log in and make sure nothing else is broken.