I posted a similar LUA error today, I only have this error in combination with DugiGuides and the quest text addons, Immersion or Storyline.

I’m no expert when it comes down to LUA programming.
But since DugiGuide’s GearAdvisor is mentioned allot in the error, it probably has something to do with that in combination with Immersion or Storyline, not sure though.
But I don’t use GearAdvisor at all, it’s turned off when I play WoW and I still get the error.