Fix NPE when hierarchy return null values
Fix NPE when hierarchy return null values

Summary:
This diff fixes a NullPointer that was being thorwn when hierarchy values are null

changelog: [internal] internal

Reviewed By: sammy-SC

Differential Revision: D30095407

fbshipit-source-id: b0a13661b4506cf94eeb5d99923d4c12cba0f972

pandiaraj44/react-native,javache/react-native,javache/react-native,janicduplessis/react-native,javache/react-native,javache/react-native,facebook/react-native,facebook/react-native,javache/react-native,pandiaraj44/react-native,pandiaraj44/react-native,facebook/react-native,pandiaraj44/react-native,facebook/react-native,pandiaraj44/react-native,pandiaraj44/react-native,facebook/react-native,pandiaraj44/react-native,facebook/react-native,javache/react-native,facebook/react-native,janicduplessis/react-native,janicduplessis/react-native,janicduplessis/react-native,janicduplessis/react-native,javache/react-native,javache/react-native,javache/react-native,facebook/react-native,janicduplessis/react-native,pandiaraj44/react-native,janicduplessis/react-native,janicduplessis/react-native,facebook/react-native