coa-template/CLIENT-BUG-GameTooltipMods.md

CoA client bug — GameTooltipMods.lua nil lineText in ModTooltipSetSpell

Component: CoA/Ascension client FrameXML mod (shipped in Data/patch-B.MPQ → Interface\FrameXML\GameTooltipMods.lua). NOT an addon — this is the client.

Realm seen: Vol'jin — CoA Beta. Reproduces on a custom-class character (e.g. Guardian) by hovering a MultiCast totem / standard action button with any tooltip-embedding addon active (TradeSkillMaster's LibExtraTip in our case, but any addon that re-fires the tooltip triggers it).

Error

Interface\FrameXML\GameTooltipMods.lua:109: attempt to index local 'lineText' (a nil value)
  GameTooltipMods.lua:109: in function `func'
  GameTooltip.lua:361 ... LibExtraTip ... SetAction
  ActionButton.lua:514 ActionButton_SetTooltip
  MultiCastActionBarFrame.lua:462 MultiCastActionButton_OnEnter
spellName = "Standard of Recovery", spellID = 500260, line index i = 4

Cause

ModTooltipSetSpell:EmbedSpell (and the custom-class totem block lower in the file) call left:GetText() and immediately index the result with no nil guard:

function ModTooltipSetSpell:EmbedSpell(left, right, spellID)
    local lineText = left:GetText()
    if lineText:find("%b@@") then          -- line 109: lineText can be nil

GameTooltipTextLeftN regions exist but return nil from GetText() when the line is empty (common on multi-line spell tooltips like totem/standard buttons — here line 4 is blank). The sibling ModTooltipSetItem:DoCustomFormatters in the same file already guards correctly:

function ModTooltipSetItem:DoCustomFormatters(left)
    if not left:GetFont() or not left:GetText() or not left:GetText():find("%b@@") then return end

ModTooltipSetSpell:EmbedSpell just needs the same guard.

Fix (one line each)

ModTooltipSetSpell:EmbedSpell — add at the top of the function:

function ModTooltipSetSpell:EmbedSpell(left, right, spellID)
    local lineText = left:GetText()
    if not lineText then return end        -- <-- add
    if lineText:find("%b@@") then
        ...

And the custom-class totem block lower down (the second local lineText = left:GetText() followed by lineText:startswith(SPELL_TOTEMS)) needs the same if not lineText then return end / if lineText and ... guard — it has the identical latent nil-deref.

No addon-side fix is possible; the crash is in client FrameXML. Reported by Sub-Net (Exiles guild) from the coa-* addon-porting work.