typo fix

src/core/PlayArea.ttslua

@@ -126,7 +126,7 @@ end
 
 function onObjectPickUp(player, object)
   -- only continue for cards
-  local objType = obj.name
+  local objType = object.name
   if objType ~= "Card" and objType ~= "CardCustom" then return end
 
   -- onCollisionExit fires first, so we have to check the card to see if it's a location we should