Stock by Attribute v4.0 addon for v1.3.5-1.3.9

[strelitzia]

I'm getting the following Warning when I use this module with PHP7.3
Use of undefined constant PRODUCTS_OPTIONS_TYPE_SELECT_SBA
The warning relates to /includes/classes/observers/class.products_with_attributes_stock.php on line 264

On a standard define, i would have done something like

if (!defined('PRODUCTS_OPTIONS_TYPE_SELECT_SBA')) {
define('PRODUCTS_OPTIONS_TYPE_SELECT_SBA', '6');
}

but, PRODUCTS_OPTIONS_TYPE_SELECT_SBA is a database stored configuration value, so how do I add a !defined line to cover this?

I'm also getting the same warning for PRODINFO_ATTRIBUTE_DYNAMIC_STATUS on line 439