WoWInterface - bizarre SetFontObject() issue

Hi all

This is a bit of a strange one.

I am the author of NewbDevBox and have struck a strange bug.
With the launch of Ulduar in Wrath Classic my addon stopped working yet the same code still works in both Classic and Retail.

The bugsack report is:

Lua Code:

23x Interface/AddOns/NewbDevBox/NewbDevBox.lua:688: attempt to index field '?' (a nil value)
[string "@Interface/AddOns/NewbDevBox/NewbDevBox.lua"]:688: in main chunk
 
Locals:
addonName = "Newb Dev Box 4 Wrath"
versionNumber = "NDB4Wrath 2.1.3.4"
ListOfDevAddons = <table> {
 1 = "BugSack"
 2 = "REHack"
 3 = "ViragDevTool"
 4 = "WowLua"
 5 = "APIInterface"
 6 = "HandleIt"
 7 = "WhatsOnTheMap"
 8 = "Cube"
 9 = "AddonUsage"
}
bugsackFunctions = <table> {
 FormatError = <function> defined @Interface/AddOns/BugSack/core.lua:218
 UpdateDisplay = <function> defined =[C]:-1
 ColorLocals = <function> defined @Interface/AddOns/BugSack/core.lua:200
 GetErrors = <function> defined @Interface/AddOns/BugSack/core.lua:167
 SendCommMessage = <function> defined @Interface/AddOns/BugSack/Libs/AceComm-3.0/AceComm-3.0.lua:87
 OnBugComm = <function> defined @Interface/AddOns/BugSack/core.lua:252
 L = <table> {
 }
 healthCheck = true
 UnregisterAllComm = <function> defined @Interface/AddOns/BugSack/Libs/CallbackHandler-1.0/CallbackHandler-1.0.lua:174
 Serialize = <function> defined @Interface/AddOns/BugSack/Libs/AceSerializer-3.0/AceSerializer-3.0.lua:122
 RegisterComm = <function> defined @Interface/AddOns/BugSack/Libs/AceComm-3.0/AceComm-3.0.lua:60
 db = <table> {
 }
 ColorStack = <function> defined @Interface/AddOns/BugSack/core.lua:186
 Deserialize = <function> defined @Interface/AddOns/BugSack/Libs/AceSerializer-3.0/AceSerializer-3.0.lua:246
 UnregisterComm = <function> defined @Interface/AddOns/BugSack/Libs/CallbackHandler-1.0/CallbackHandler-1.0.lua:153
 OpenSack = <function> defined @Interface/AddOns/BugSack/sack.lua:458
 SendBugsToUser = <function> defined @Interface/AddOns/BugSack/core.lua:238
 frame = Frame {
 }
 CloseSack = <function> defined @Interface/AddOns/BugSack/sack.lua:454
 Reset = <function> defined @Interface/AddOns/BugSack/core.lua:231
}
SortedNewbDevBoxButtonTable = <table> {
}
stringNewbDevBox = "Newb Dev Box"
stringKeyBindings = "Keybindings"
stringToggleFrame = "Toggle Frame"
stringReload = "Reload"
stringLogout = "Logout"
stringFStack = "FStack"
stringETrace = "ETrace"
stringChatLog = "Chat Log"
stringCombatLog = "Combat Log"
stringClearChat = "Clear Chat"
stringChatSpacer = "Chat Spacer"
stringETraceStart = "ETrace Start"
stringETraceStop = "ETrace Stop"
stringExit = "Exit"
stringBugSack = "Bug Sack"
stringBugSackClear = "Clear Bug Sack"
stringWoWLuaButton = "WoW Lua"
stringREHackButton = "REHack"
stringViragDevTool = "Virag Dev Tool"
stringAPIInterface = "API Interface"
stringHandleIt = "Handle It"
stringVersion = "Version"
stringVersionPrint = "Current Version -:"
stringFrameScale = "% Button Box Scale"
stringFrameOpacity = "% Button Box Opacity"
stringWhatsOnTheMapButton = "Whats On The Map"
stringCubeCodeButton = "Cube Code"
stringCubeBrowserButton = "Cube Browser"
stringAddonUsageButton = "Addon Usage"
TextDimensionList = <table> {
 checkBoxFont = FocusFontSmall {
 }
 secureButtonTemplate = "SecureActionButtonTemplate, GameMenuButtonTemplate"
 colourBackdrop = <table> {
 }
 buttonTemplate = "GameMenuButtonTemplate"
 buttonFont = Game13FontShadow {
 }
 checkBoxTextColour = "|cffffd100"
 addonColour = "|cff00ff00"
 disabledTextColour = "|cff918f8e"
 keybindButtonFont = ErrorFont {
 }
 colourBorder = <table> {
 }
}
NewbDevBoxTitle = NewbDevBoxTitle {
 0 = <userdata>
}
NewbDevBoxButton = NewbDevBoxButton {
 0 = <userdata>
}
TextStringList = <table> {
 btnBugSackClearButton = "Clear Bug Sack"
 btnChatSpacer = "Chat Spacer"
 printVersion = "|cff00ff00Current Version -:"
 addonLoaded = "|cff00ff00 *** Newb Dev Box 4 Wrath - NDB4Wrath 2.1.3.4 Loaded *** 
"
 btnWhatsOnTheMapButton = "Whats On The Map"
 cbAPIInterfaceButton = " API Interface"
 cbLogout = " Logout"
 btnVersionButton = "Version"
 cbChatLog = " Chat Log"
 btnETrace = "ETrace"
 cbCubeBrowserButton = " Cube Browser"
 cbCombatLog = " Combat Log"
 btnAPIInterfaceButton = "API Interface"
 btnViragDevToolButton = "Virag Dev Tool"
 btnLogout = "Logout"
 cbClearChat = " Clear Chat"
 textBoxScale = "% Button Box Scale"
 cbBugSackClearButton = " Clear Bug Sack"
 printChatSpacer = "|cff00ff00********************************************************"
 btnEtraceStop = "ETrace Stop"
 cbWoWLuaButton = " WoW Lua"
 btnCubeButton = "Cube Code"

The error report points to line 688.

Here is the checkbox code chunk:

Lua Code:

local NewbDevBoxInterfaceFramecbLogoutButton =
    CreateFrame(
    "CheckButton",
    "NewbDevBoxInterfaceFramecbLogoutButton",
    NewbDevBoxInterfaceFrame,
    "UICheckButtonTemplate"
)
NewbDevBoxInterfaceFramecbLogoutButton:SetSize(NumberList.checkBoxSize, NumberList.checkBoxSize)
NewbDevBoxInterfaceFramecbLogoutButton:SetPoint(
    "TOPLEFT",
    NewbDevBoxInterfaceFrame,
    "TOPLEFT",
    NumberList.checkBoxMainSideGap,
    NumberList.checkBoxMainTopGap
)
NewbDevBoxInterfaceFramecbLogoutButton.text:SetFontObject(TextDimensionList.checkBoxFont)
NewbDevBoxInterfaceFramecbLogoutButton.text:SetText(TextStringList.cbLogout)
NewbDevBoxInterfaceFramecbLogoutButton:SetScript(
    "OnClick",
    function()
        if NewbDevBoxDisplayButtonsList[1].LogoutButton then
            NewbDevBoxDisplayButtonsList[1].LogoutButton = false
        else
            NewbDevBoxDisplayButtonsList[1].LogoutButton = true
        end
        buttonFrameButtonLayout()
    end
)

Line 16 is the line 688 in my full code is posted on my pastebin.

Really shaking my head over this one.