Admin action defined outside of ModelAdmin Class doesn't work

[mav1984]

Describe the bug
A function (django admin action) defined outside of ModelAdmin Class doesn't work with django-admin-confirm.

It raises
TypeError at /admin/demo/demo/
cannot unpack non-iterable NoneType objec

To Reproduce

1. Define admin action function outside ModelAdmin class
2. Click on action in admin site

Expected behavior

confirmation page works

Screenshots

Versions:

• Version 1.0.1

Additional context
The same code was in #37 but with another problem.