diff --git a/Kui_Nameplates/Modules/Castbar.lua b/Kui_Nameplates/Modules/Castbar.lua
index c0ef8c6..5fd09cd 100644
--- a/Kui_Nameplates/Modules/Castbar.lua
+++ b/Kui_Nameplates/Modules/Castbar.lua
@@ -416,12 +416,14 @@ function mod:OnInitialize()
 			end
 		)
 	end
-	InterfaceOptionsFrame:HookScript(
-		"OnHide",
-		function()
-			SetCVars()
-		end
-	)
+	if InterfaceOptionsFrame then
+		InterfaceOptionsFrame:HookScript(
+			"OnHide",
+			function()
+				SetCVars()
+			end
+		)
+	end
 
 	SetCVars()
 end
diff --git a/Kui_Nameplates/Modules/ClassColours.lua b/Kui_Nameplates/Modules/ClassColours.lua
index 7f8402a..5bed92c 100644
--- a/Kui_Nameplates/Modules/ClassColours.lua
+++ b/Kui_Nameplates/Modules/ClassColours.lua
@@ -106,7 +106,9 @@ function mod:OnInitialize()
 			end
 		end)
 	end
-	InterfaceOptionsFrame:HookScript("OnHide", function() SetCVars() end)
+	if InterfaceOptionsFrame then
+		InterfaceOptionsFrame:HookScript("OnHide", function() SetCVars() end)
+	end
 	SetCVars()
 end
 function mod:OnEnable()
diff --git a/Kui_Nameplates/Modules/TankMode.lua b/Kui_Nameplates/Modules/TankMode.lua
index a181fbf..e1477ce 100644
--- a/Kui_Nameplates/Modules/TankMode.lua
+++ b/Kui_Nameplates/Modules/TankMode.lua
@@ -8,7 +8,10 @@ local addon = LibStub("AceAddon-3.0"):GetAddon("KuiNameplates")
 local mod = addon:NewModule("TankMode", addon.Prototype, "AceEvent-3.0")
 local L = LibStub("AceLocale-3.0"):GetLocale("KuiNameplates")
 
-local class, tankmode = select(2, UnitClass("player")), nil
+-- `class` is resolved in mod:OnEnable() rather than at file scope: on the CoA
+-- client this file can be parsed before PLAYER_LOGIN, when UnitClass("player")
+-- returns nil and would otherwise leave `class` permanently nil.
+local class, tankmode = nil, nil
 
 local profile_tankmode
 
@@ -137,6 +140,10 @@ do
 		return tankTalents >= 3
 	end
 
+	-- NOTE: only vanilla 3.3.5 classes are matched below. CoA custom classes
+	-- will fall through to DAMAGER in mod:Update(). If a CoA-specific tank /
+	-- healer class table becomes available we should consult it here instead
+	-- of (or in addition to) the hard-coded class strings.
 	local function IsTank()
 		return (class == "WARRIOR" and select(3, GetTalentTabInfo(3)) >= 51) or
 			(class == "DEATHKNIGHT" and IsDeathKnightTank()) or
@@ -144,6 +151,7 @@ do
 			(class == "DRUID" and select(3, GetTalentTabInfo(2)) >= 51 and IsDruidTank())
 	end
 
+	-- See IsTank() note: CoA custom healer classes fall through to DAMAGER.
 	local function IsHealer()
 		return (class == "PALADIN" and select(3, GetTalentTabInfo(1)) >= 51) or
 			(class == "SHAMAN" and select(3, GetTalentTabInfo(3)) >= 51) or