However, when I tried to load up the game with the addon installed, it tells me QuestHelper has broken. You may have to restart WoW. Type '/qh error" for a detailed error message.
[C]: in function `AddToBlizOptions'
InterfaceAddOnsQuestHelperconfig.lua:78: in function `SetupGUI'
InterfaceAddOnsQuestHelperconfig.lua:66: in function `OnInit'
InterfaceAddOnsQuestHelperconfig.lua:56: in function `func'
InterfaceAddOnsQuestHelpermanager_event.lua:43: in function <InterfaceAddOnsQuestHelpermanager_event.lua:25>
InterfaceAddOnsQuestHelpermanager_event.lua:58: in function <InterfaceAddOnsQuestHelpermanager_event.lua:52>
just downloaded it to test it. for me it works without error or crash.
try disabling all other addons and see if theres still an error. if it begins working then figure out which addon exacly causes the problem (and from where you got it) and post it here.
if there is still an error with all other addons disabled... you sure you downloaded the addon from the thread you posted, from this github link here? https://github.com/LezChap/QuestHelper_Onyxia
maybe download it again to make sure its really this version