WowAce

"SexyCooldown-0.6.16\\Modules\\Spells.lua:15: attempt to index a nil value\nSexyCooldown-0.6.16\\Modules\\Spells.lua:156: in function `CacheSpells'\nSexyCooldown-0.6.16\\Modules\\Spells.lua:57: in function <Interface\\AddOns\\SexyCooldown\\Modules\\Spells.lua:56>\n(tail call): ?:\n<in C code>: ?\n<string>:\"safecall Dispatcher[1]\":9: in function <[string \"safecall Dispatcher[1]\"]:5>\n(tail call): ?:\nAceAddon-3.0-5 (Ace3):539: in function `EnableAddon'\nAceAddon-3.0-5 (Ace3):551: in function `EnableAddon'\nAceAddon-3.0-5 (Ace3):629: in function <Interface\\AddOns\\Ace3\\AceAddon-3.0\\AceAddon-3.0.lua:615>\n<in C code>: in function `LoadAddOn'\nInterface\\FrameXML\\UIParent.lua:242: in function `UIParentLoadAddOn':\nInterface\\FrameXML\\UIParent.lua:265: in function `CombatLog_LoadUI':\nInterface\\FrameXML\\UIParent.lua:519: in function <Interface\\FrameXML\\UIParent.lua:492>:\n\n  ---",
            ["type"] = "error",

There's already an open ticket for this issue: http://www.wowace.com/addons/sexycooldown/tickets/49-error-on-load-in-wow-4-0-1/