Describe the bug
As an admin when trying to add a sortition component to a participatory process the application crashes.
To Reproduce
Steps to reproduce the behavior:

1. Go to http://staging.decidim.codegram.com/admin/participatory_processes/test/components
2. Click on 'Add component'
3. Scroll down to 'Sortitions'
4. Click on 'add component'
5. See error

Expected behavior
The component should deploy ok.

Screenshots