I just did this and still getting errors. Same ones I attached. The only enabled Addon is Duigis. 

    I did both the Repair then when that didn’t work I did the reinstall. Same issue. Seems to happen when I open a map or the waypoint arrow gets updated. I can watch it climb into the 4,000 counts  The main error I keep seeing is attempt to call method ‘AssignQuestNumber’ (a nil value).

    This almost seems character specific. I dont get this error when playing my lower level characters in WOTLK classic, and I dont get it in classic era or retail, just on my character currently leveling in Zangarmarsh.