dnadesign/silverstripe-shop — pull request #1 by halkyon (2014-03-07 01:17:51+00:00)
Title: Fixing issue where setHasEmptyDefault is called on non-DropdownField

This field might not specifically be a DropdownField, and if that's the
case then an error will be thrown because setHasEmptyDefault isn't
available.

Fix this by checking the field is an instance of DropdownField first.