ensure collector results are evaluated

src/Convert/Traverse.hs

@@ -120,7 +120,7 @@ unmonad traverser mapper = runIdentity . traverser (return . mapper)
 collectify :: Monad m => (MapperM m a -> MapperM m b) -> CollectorM m a -> CollectorM m b
 collectify traverser collector =
     traverser mapper >=> \_ -> return ()
-    where mapper x = collector x >> return x
+    where mapper x = collector x >>= \() -> return x
 
 traverseDescriptionsM :: Monad m => MapperM m Description -> MapperM m AST
 traverseDescriptionsM = mapM