check if resolve_field returns nullptr in remove builder
check if resolve_field returns nullptr in remove builder

Summary: If it does, let it fall through to later checks

Reviewed By: thezhangwei

Differential Revision: D38250843

fbshipit-source-id: d3e3cadf4e30d9e61fcb3ec77b0dee30cd79d795

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex