[litho] Handle non-existing caller path

Reviewed By: skcho

Differential Revision: D26975222

fbshipit-source-id: 758c4f0b3

infer/src/checkers/LithoDomain.ml

@@ -130,9 +130,10 @@ module Created = struct
           | CreatedLocation.ByCreateMethod _ ->
               append_one caller_return callee_return acc
           | CreatedLocation.ByParameter path ->
-              let caller_path = SubstPathMap.find path map in
-              Option.value_map (find_opt caller_path caller) ~default:acc ~f:(fun caller_created ->
-                  append caller_return caller_created acc )
+              SubstPathMap.find_opt path map
+              |> Option.value_map ~default:acc ~f:(fun caller_path ->
+                     Option.value_map (find_opt caller_path caller) ~default:acc
+                       ~f:(fun caller_created -> append caller_return caller_created acc) )
         in
         CreatedLocations.fold accum_subst callee_returns acc )