28x SharedXML/Color.lua:61: bad argument #2 to 'format' (string expected, got nil)
[string "=[C]"]: in function format' [string "@SharedXML/Color.lua"]:61: in function <SharedXML/Color.lua:60> [string "=(tail call)"]: ? [string "@TipTac/ttStyle.lua"]:346: in function GeneratePetLines'
[string "@TipTac/ttStyle.lua"]:419: in function ModifyUnitTooltip' [string "@TipTac/ttStyle.lua"]:655: in function ?'
[string "@TipTac/libs/LibFroznFunctions-1.0-15/LibFroznFunctions-1.0.lua"]:889: in function FireGroupEvent' [string "@TipTac/ttCore.lua"]:2647: in function SetUnitAppearanceToTip'
[string "@TipTac/ttCore.lua"]:2750: in function ?' [string "@TipTac/libs/LibFroznFunctions-1.0-15/LibFroznFunctions-1.0.lua"]:889: in function FireGroupEvent'
[string "@TipTac/ttCore.lua"]:1507: in function SetCurrentDisplayParams' [string "@TipTac/ttCore.lua"]:1382: in function <TipTac/ttCore.lua:1381> ... [string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:182: in function <SharedXML/Tooltip/TooltipDataHandler.lua:178> [string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:218: in function <SharedXML/Tooltip/TooltipDataHandler.lua:208> [string "=[C]"]: in function SetAttribute'
[string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:243: in function <SharedXML/Tooltip/TooltipDataHandler.lua:236>
[string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:389: in function <SharedXML/Tooltip/TooltipDataHandler.lua:339>
[string "=[C]"]: in function securecallfunction' [string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:336: in function ProcessInfo'
[string "@FrameXML/GameTooltip.lua"]:1092: in function `SetWorldCursor'
[string "@FrameXML/UIParent.lua"]:1484: in function <FrameXML/UIParent.lua:1407>
[string "=[C]"]: ?

Locals:
(*temporary) = "|c%s%s|r"
(*temporary) = "ffffffff"
(*temporary) = nil
(*temporary) = "string expected, got nil"

It happend everytime when i mouseover an Animaltrainer like Enok or someoneelse

when i disabel "special" - enable battle pet tips
then no error apear

I can't reproduce this on my side. The color which is used here is the one in options under "Colors->Race & Creature Type Color". Is there a proper color set?

Edit:

It seems that it's not a problem with the race color, instead the pet type determined by UnitBattlePetType() seems wrong. It's not a general problem but with some special pets.

I'm on it...

I'm getting this when mousing over an Argent Gruntling.

It seems that it's currently a blizzard bug. The return values for UnitBattlePetType() are currently off by one and returns a value range of 0 - 9 instead if the original 1 - 10.

For pet types 2 - 10 the pet type shown is wrong, for humanoid pets (pet type 1) this error occurs.

Source: https://us.forums.blizzard.com/en/wow/t/lua-error-when-clicking-on-humanoid-battle-pet/1707965

This function is actually only used on blizzards side in the target frame, where the pet type is also wrong (cats will be shown as pet type elemental instead of beast).

I think I will wait a few days for blizzard to fix this.

As of today the bug has been fixed by blizzard. Working fine now after latest update.