The application section of the circulation policy editor does not behave as expected.

[pronguen]

Describe the bug
In the circulation policy, section Application, the editor does not behave as expected. When unchecking the last item type for a patron type, the list of item types disappear.

To Reproduce

1. Log in as system librarian
2. Edit a circulation policy
3. Check a patron type > item types are displayed below
4. Check only one item type for this patron type
5. Uncheck this item type > item types disappear

Expected behavior
At step 5, the item type list should not disappear.

Context

• server: ilspilot.test.rero.ch
• version: v0.12.0

Additional context
Proposed by pilot libraries