Steps:

1. Go to Admin/Roles
2. Add a new Role
3. Add a policy: User/Register and click Save

Actual Result:

Error 500: An exception has been thrown during the rendering of a template ("Argument 'user/register' has a bad state: policyMap configuration is referring to non existing identifier: 0").

Expected result:

Policy is added without problems.

In the ezpublish-kernel, there is an exception which is thrown for $identifier = 0 for $module = 'user' and $function = 'register'.
https://github.com/ezsystems/ezpublish-kernel/blob/master/eZ/Publish/Core/Repository/RoleService.php#L1321
https://github.com/ezsystems/ezpublish-kernel/blob/master/eZ/Publish/Core/Repository/Helper/LimitationService.php#L51