error on saving post with empty gallery

Hi Navneil,
I had a problem saving a post with an empty gallery.
It was throwing an error:

Notice: Undefined index: gallery in /Users/***/*****/htdocs/steelroots/wp-content/plugins/navz-photo-gallery/fields/acf-photo_gallery-v4.php on line 15

so I changed line 15 in fields/acf-photo_gallery-v4.php to include a check to see if a gallery was actually being posted:

$ids = !empty($field) && isset($_POST[$field_id])? $_POST[$field_id]: null;

I hope this is helpful.
Cheers!