I've been running into this error occasionally:
Code:
Blizzard_GlyphUI\Blizzard_GlyphUI-1.0.lua:174: attempt to index global "PlayerTalentFrame" (a nil value)
Blizzard_GlyphUI\Blizzard_GlyphUI-1.0.lua:174: in function "GlyphFrame_Update"
Blizzard_GlyphUI\Blizzard_GlyphUI-1.0.lua:91: in function <Blizzard_GlyphUI\Blizzard_GlyphUI.lua:80>
Tracked it down yesterday, it turns out to be a bit of careless coding in Blizzard_GlyphUI. The writeup is at
http://us.battle.net/wow/en/forum/topic/6470967787 but I wanted to post a note here, since the search engine on Blizzard's forum is often temperamental.
Anybody with write access to Blizzard's FrameXML repo :-p feel free to add the appropriate check.