Description of problem:

Recently, we introduced the ability to reduce the number of permissions that are enforcer checks against during enforcement. It seems like this lead to an error whenever we attempt to filter for a permission that is not defined through the REST API or the CSV file. 

error: Policy check failed with Error: Entity reference must not be empty {"plugin":"permission","service":"backstage","timestamp":"2024-04-23 13:08:41"}

This error is happening because the enforcer is being loaded with no permissions at all, which results in it being unable to perform any checks.

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

1. Create a CSV file with the following

   • g, user:default/<YOUR_USERNAME>, role:default/policy-error
     p, role:default/policy-error, catalog-entity, read, allow

1. Enable the RBAC Backend plugin using the following

   • permission:
       enabled: true
       rbac:
         policies-csv-file: ../<PATH>/<TO>/<CSV-FILE>.csv

1. Attempt to navigate to the home page of the catalog

Actual results:

Throws an error for the permission `catalog.entity.create` and denies the request.

Expected results:

It should just deny the request without throwing an error

Reproducibility (Always/Intermittent/Only Once):

Build Details:

Additional info (Such as Logs, Screenshots, etc):