Adding a field_map field to a class that extends GFFeedAddOn causes error

I’ve created a custom Feed Addon. This class extends \GFFeedAddOn. In this class I overrule the function feed_settings_fields() and I add a new field_map field. But whenever I want to show this in my feed, I get a javascript console error: initializeFieldMap is not defined
This error was caused since version

Hello @gopublic - be sure you are using the very latest release from here:

If so, and you continue to have issues, please open a support ticket:

Thank you.