Perch Shop 1.2.6 – array_key_exists() warning

Hi

I've just updated a dev copy to the latest Perch RW with Shop, Members & Forms.

I am getting the following warning (for each form field on a edit page) when trying to add anything new in the Shop app: Products, Shipping, Tax etc - I've tried them all.

Warning/Users/ellimondo/Dropbox/Sites/ellipress/dev.ellipress.co.uk/perch/core/lib/PerchFieldType.class.php228

: array_key_exists() expects parameter 2 to be array, boolean given in on line 

I've switched PHP versions back as far as PHP 5.6 but the warning is still there.

Form submits fine – just the warning so thought I should log it here.

Perch Runway: 3.1, PHP: 7.2.1, MySQL: mysqlnd 5.0.12-dev - 20150407 - $Id: b396954eeb2d1d9ed7902b8bae237b287f21ad9e $, with PDO
Server OS: Darwin, apache2handler
Installed apps: content (3.1), assets (3.1), categories (3.1), perch_forms (1.11), perch_shop_orders (1.2.6), perch_shop_products (1.2.6), perch_shop (1.2.6), perch_members (1.6.3), pipit_catalog (1.2.0), perch_mailchimp (3.1)
App runtimes: <?php $apps_list = [ 'perch_mailchimp', 'perch_members', 'perch_shop', 'perch_forms', ];
PERCH_LOGINPATH: /perch
PERCH_PATH: /Users/ellimondo/Dropbox/Sites/ellipress/dev.ellipress.co.uk/perch
PERCH_CORE: /Users/ellimondo/Dropbox/Sites/ellipress/dev.ellipress.co.uk/perch/core
PERCH_RESFILEPATH: /Users/ellimondo/Dropbox/Sites/ellipress/dev.ellipress.co.uk/perch/resources
Image manipulation: GD
PHP limits: Max upload 32M, Max POST 8M, Memory: 128M, Total max file upload: 8M
F1: 3b606135b33e6a102526838f4152a807
Resource folder writeable: Yes
HTTP_HOST: dev.ellipress.co.uk
DOCUMENT_ROOT: /Users/ellimondo/Dropbox/Sites/ellipress/dev.ellipress.co.uk
REQUEST_URI: /perch/core/settings/diagnostics/
SCRIPT_NAME: /perch/core/settings/diagnostics/index.php