Add laser tunnel lock-key combination

src/Dodge/PlacementSpot.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase #-}
 module Dodge.PlacementSpot where
 import Dodge.LevelGen.Data
 import Geometry
@@ -39,7 +40,7 @@ unusedSpotAwayFromLink x = PSPos f (const id) Nothing
 
 setFallback :: Placement -> Placement -> Placement
 setFallback fallback plmnt = plmnt
-    & plSpot . psFallback .~ Just fallback
+    & plSpot . psFallback %~ maybe (Just fallback) Just
     & plIDCont %~ fmap (fmap $ setFallback fallback)
 
 unusedOffPathAwayFromLink :: Float -> PlacementSpot
@@ -88,7 +89,7 @@ useRoomPosCond t rp _
     a = _rpDir rp
 
 unusedLnkToPS :: RoomPos -> Room -> Maybe (PlacementSpot,RoomPos)
-unusedLnkToPS = useRoomPosCond $ \rp -> case rp of
+unusedLnkToPS = useRoomPosCond $ \case
     UnusedLink {} -> True
     _ -> False