[Wimpface]

Just installed HaveIDoneThat to try it out, and found that you need to apply the fix Phanx posted on the ticket or it will throw errors all over the place (even in other files like items.lua and config.lua) and won't load the extra tab shown in Phanx screenshot.

In compare.lua, you want to replace this block (line 15-24)

function mod:OnLoad()
    self:InitDB()
 
    for tooltip in pairs(hook_tooltips) do
        hooksecurefunc(tooltip, "SetHyperlink", self.OnSetHyperlink)
        hooksecurefunc(tooltip, "Hide", self.OnTooltipHide)
    end
end
 
local player_guid = strsub(UnitGUID("player"), 3)

With the one Phanx suggested on the ticket:

local player_guid
 
function mod:OnLoad()
    self:InitDB()
end
 
function mod:OnLogin()
    player_guid = strsub(UnitGUID("player"), 3)
 
    for tooltip in pairs(hook_tooltips) do
        hooksecurefunc(tooltip, "SetHyperlink", self.OnSetHyperlink)
        hooksecurefunc(tooltip, "Hide", self.OnTooltipHide)
    end
end