githooks - Git hook not completing on Github Desktop for mac -

my hook works fine on git cli.

adding echo 'running precommit hook' > ~/desktop/hello.txt hook makes file appear when commit gui, pre-commit running.

however next line in hook gulp --production. never seems run, , can't establish why.

including full path gulp /usr/local/bin/gulp --production doesn't fix it.

replacing shebang #!/bin/sh #!/usr/bin/env sh doesn't fix it.

.git/hooks/pre-commit permissions -rwxr-xr-x.