Just received this error on the unit frames. I was in Crimson Badlands and targeted the spiders that a dominion was killing. I am exile. The unit frames disappeared after the error and problem was resolved with a /reloadui

...tar\Addons\CandyUI_UnitFrames\CandyUI_UnitFrames.lua:813: attempt to index field '?' (a nil value)
stack trace:
...tar\Addons\CandyUI_UnitFrames\CandyUI_UnitFrames.lua:813: in function 'UpdateClusters'
...tar\Addons\CandyUI_UnitFrames\CandyUI_UnitFrames.lua:235: in function <...tar\Addons\CandyUI_UnitFrames\CandyUI_UnitFrames.lua:222>

No I have not received this error again. It was just that one time.

Im having trouble figuring this problem out. Are you still getting it?

Hmmm. Well if it comes up again let me know and open another issue. Thanks!