[Normalizer][Fix] Restore try-catch around Flow_js calls
[Normalizer][Fix] Restore try-catch around Flow_js calls

Summary: Better be safe.

Reviewed By: pakoito

Differential Revision: D10466778

fbshipit-source-id: 31e08f0d3ea561d0aaaff54b139892ffb2ec0cb3

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow