Fix `Item:Usable` and `Spell:Castable`

src/Item/Item.lua

@@ -366,8 +366,8 @@ function Item:Usable()
     if not self:EvaluateTraits() then
         return false
     end
-    if self:GetUsableFunction() then
+    if self:GetUsableFunction() and not self:GetUsableFunction()(self) then
-        return self:GetUsableFunction()(self)
+        return false
     end
 
     return self:IsEquippedAndUsable()

src/Spell/Spell.lua

@@ -421,9 +421,8 @@ function Spell:Castable()
     if not self:EvaluateTraits() then
         return false
     end
-    if self:GetCastableFunction() then
+    if self:GetCastableFunction() and not self:GetCastableFunction()(self) then
-        return self:GetCastableFunction()(self) and
+        return false
-            self:IsKnownAndUsable(type(self.traits.cast.override) ~= nil and self.traits.cast.override or nil)
     end
 
     return self:IsKnownAndUsable(type(self.traits.cast.override) ~= nil and self.traits.cast.override or nil)