This bug started with the new 8.2 patch, wasn't happening before. Version is the latest one to date (8.15.373).

No other addons active.

This is what Swatter shows:

Date: 2019-06-25 19:34:05
ID: 1
Error occured in: Global
Count: 6
Message: ...ddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua line 587:
attempt to index upvalue 'GameTooltipFrameTextLeft3' (a nil value)
Debug:
...ddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua:587: RewardIsArtifactPower()
...ddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua:773: GetQuestReward_Item()
...ddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua:273: GetOrLoadQuestData()
...Ons\WorldQuestTracker\WorldQuestTracker_WorldMap.lua:1286: UpdateWorldQuestsOnWorldMap()
...Ons\WorldQuestTracker\WorldQuestTracker_WorldMap.lua:846:
...Ons\WorldQuestTracker\WorldQuestTracker_WorldMap.lua:844
..\SharedXML\C_TimerAugment.lua:16:
..\SharedXML\C_TimerAugment.lua:14
Locals:
itemLink = "[Ironcrest Bulwark]"
text = "Item Level 280"
(*temporary) = nil
(*temporary) = nil
(*temporary) = defined =[C]:-1
(*temporary) = defined *:OnShow:1
(*temporary) = WorldQuestTrackerScanTooltipMoneyFrame1 {
small = 1
staticMoney = 458123
info =

{
}
vadjust = 0
trialErrorButton = WorldQuestTrackerScanTooltipMoneyFrame1TrialErrorButton {
}
0 =
moneyType = "STATIC"
}
(*temporary) = defined @interface\FrameXML\MoneyFrame.lua:282
(*temporary) = WorldQuestTrackerScanTooltipMoneyFrame1 {
small = 1
staticMoney = 458123
info = {
}
vadjust = 0
trialErrorButton = WorldQuestTrackerScanTooltipMoneyFrame1TrialErrorButton {
}
0 =
moneyType = "STATIC"
}
(*temporary) = "attempt to index upvalue 'GameTooltipFrameTextLeft3' (a nil value)"
WorldQuestTracker = {
LastUpdate = 362333.349000
modules = {
}
CancelTimer = defined @interface\AddOns\WorldQuestTracker\libs\AceTimer-3.0\AceTimer-3.0.lua:147
QUEST_POI_FRAME_HEIGHT = 1
Cache_ShownQuestOnWorldMap = {
}
AllCharactersQuests_Add = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker.lua:707
UpdateArrowFrequence = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_FrameAPI.lua:94
GetTemplate = defined @interface\AddOns\WorldQuestTracker\libs\DF\fw.lua:1460
mapTables = {
}
CommFunctions = {
}
RareWidgetOnClick = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_RareFinder.lua:710
ScheduleTimer = defined @interface\AddOns\WorldQuestTracker\libs\AceTimer-3.0\AceTimer-3.0.lua:94
IsCurrentMapQuestHub = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua:135
SavedQuestList_GetList = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker.lua:659
CreateGlowOverlay = defined @interface\AddOns\WorldQuestTracker\libs\DF\fw.lua:2024
ShowPanicWarning = defined @interface\AddOns\WorldQuestTracker\libs\DF\panel.lua:1800
db = {
}
CheckAddToTracker = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_FrameAPI.lua:576
UnregisterAllComm = defined @interface\AddOns\WorldQuestTracker\libs\CallbackHandler-1.0\CallbackHandler-1.0.lua:200
SetEnabledState = defined @interface\AddOns\WorldQuestTracker\libs\AceAddon-3.0\AceAddon-3.0.lua:455
ShowTutorialAlertFrame = defined @interface\AddOns\WorldQuestTracker\libs\DF\fw.lua:1137
ShowDefaultPinForQuest = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_FrameAPI.lua:65
ZoneWidgetPool = {
}
WorldMapQuestCounter = 8
GetQuestReward_Resource = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua:671
NewModule = defined @interface\AddOns\WorldQuestTracker\libs\AceAddon-3.0\AceAddon-3.0.lua:266
CanShowWorldMapWidgets = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua:173
ColorPick = defined @interface\AddOns\WorldQuestTracker\libs\DF\panel.lua:1377
CreateSwitch = defined @interface\AddOns\WorldQuestTracker\libs\DF\slider.lua:922
BuildTooltip = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_Tracker.lua:472
GetTrackedQuestsOnDB = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker.lua:122
UpdateZoneWidgetAnchors = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_ZoneMap.lua:500
DumpTrackingList = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_FrameAPI.lua:40
GetName = defined @interface\AddOns\WorldQuestTracker\libs\AceAddon-3.0\AceAddon-3.0.lua:310
name = "WorldQuestTrackerAddon"
GetMapInfo = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_MapAPI.lua:149
OnQuestButtonClick = defined @interface\AddOns\WorldQuestTracker\WorldQuestTracker_FrameAPI.lua:643
AddOns:
Swatter, v7.3.1 (<%codename%>)
WorldQuestTracker, v
BlizRuntimeLib_enUS v8.2.0.80200
(ck=62)