Simplify expression

Author: OlivierNicole

compiler/lib/js_output.ml

@@ -1980,11 +1980,7 @@ let program ?(accept_unnamed_var = false) f ?source_map p =
     | Some sm ->
         let sources = hashtbl_to_list files in
         let names = hashtbl_to_list names in
-        let sources_contents =
-          let open Option.Syntax in
-          let* r = contents in
-          Option.return (List.rev !r)
-        in
+        let sources_contents = Option.map ~f:(fun x -> List.rev !x) contents in
         let sources =
           List.map sources ~f:(fun filename ->
               match Builtins.find filename with