Trying to open Cooking from hotbar in CATA-classic did this one time

1x …lizzard_TradeSkillUI/Wrath/Blizzard_TradeSkillUI.lua:73: attempt to index field ‘SubClassDropdown’ (a nil value)
[string “@Blizzard_TradeSkillUI/Wrath/Blizzard_TradeSkillUI.lua”]:73: in function TradeSkillFrame_SetupSubClassDropdown' [string "@Blizzard_TradeSkillUI/Wrath/Blizzard_TradeSkillUI.lua"]:164: in function updateFunction’
[string “@Blizzard_SharedXML/SecureScrollTemplates.lua”]:232: in function FauxScrollFrame_OnVerticalScroll' [string "*Blizzard_TradeSkillUI.xml:532_OnVerticalScroll"]:1: in function <[string "*Blizzard_TradeSkillUI.xml:532_OnVerticalSc..."]:1> [string "=[C]"]: in function SetVerticalScroll’
[string “@Blizzard_SharedXML/SecureScrollTemplates.lua”]:24: in function <Blizzard_SharedXML/SecureScrollTemplates.lua:23>
[string “=[C]”]: in function SetMinMaxValues' [string "@Blizzard_TradeSkillUI/Wrath/Blizzard_TradeSkillUI.lua"]:36: in function <...lizzard_TradeSkillUI/Wrath/Blizzard_TradeSkillUI.lua:26> [string "=[C]"]: ? [string "=[C]"]: in function Show’
[string “@Blizzard_UIParentPanelManager/Classic/UIParentPanelManager_Shared.lua”]:603: in function SetUIPanel' [string "@Blizzard_UIParentPanelManager/Classic/UIParentPanelManager_Shared.lua"]:448: in function ShowUIPanel’
[string “@Blizzard_UIParentPanelManager/Classic/UIParentPanelManager_Shared.lua”]:316: in function <…PanelManager/Classic/UIParentPanelManager_Shared.lua:312>
[string “=[C]”]: in function SetAttribute' [string "@Blizzard_UIParentPanelManager/Classic/UIParentPanelManager_Shared.lua"]:1091: in function ShowUIPanel’
[string “@Blizzard_UIParent/Cata/UIParent.lua”]:1158: in function <Blizzard_UIParent/Cata/UIParent.lua:657>
[string “=[C]”]: in function UseAction' [string "@Blizzard_FrameXML/Classic/SecureTemplates.lua"]:329: in function handler’
[string “@Blizzard_FrameXML/Classic/SecureTemplates.lua”]:612: in function `SecureActionButton_OnClick’
[string “*ActionBarFrame.xml:15_OnClick”]:4: in function <[string “*ActionBarFrame.xml:15_OnClick”]:1>

Locals:
self = TradeSkillListScrollFrame {
ScrollBar = TradeSkillListScrollFrameScrollBar {
}
offset = 0
ScrollChildFrame = TradeSkillListScrollFrameScrollChildFrame {
}
}
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = “attempt to index field ‘SubClassDropdown’ (a nil value)”

WoW-CATA-classic v4.4.2
I have many addons just none that effect cooking as far I know…

!BugGrabber, BugSack, Auctionator, AutoProfitX2, AutoRepair,
BLU (Better Level Up)(sound effects for various things like achievements or on level up),
Broker_PlayedTime, Chattynator, CombatMusic, DejaClassicStats, IceHUD, IceHUD_Options, InFlight (taxi timer), PlayedTimeMinimapClock, Questie, RangeDisplay, RangeDisplay_Options, RepairBroker, ThreatClassic2(disabled)
tullaRange, tullaRange_Config, WhatsTraining, WIM (WoW Instant Messenger v3),
XPBarText.
thats all the addons I use. hope it helps… all is up to date.
It just happened again this time for FirstAid on a different character on Pagle