Assign Object Permissions to Role Fails

### Describe the bug

When attempting to assign object permissions to a user, it fails with a "Response returned an error code" error. The console shows a 404 error.

### How to reproduce

1. Create a service/user account
2. Open the new user
3. Go to "Permissions"
4. Click "Assign Object Permission"
5. Set some permissions without selecting a role
6. Click "Assign"

### Expected behavior

If specifying a role is necessary, the form field should properly indicate this and provide the user with proper indication that it needs to be selected if they try to submit the form invalidly.

If not, it shouldn't result in an error. It should submit properly.

### Screenshots

### Additional context

_No response_

### Deployment Method

Docker

### Version

2025.12.1

### Relevant log output

```shell
RoleObjectPermissionForm.ts:60
GET https:///api/v3/rbac/permissions/assigned_by_roles/assign/ 404 (Not Found)
installHook.js:1 [WARN] (api/-default): 404 POST /api/v3/rbac/permissions/assigned_by_roles//assign/
installHook.js:1 authentik/forms: API rejected the form submission due to an invalid field that doesn't appear to be in the form. This is likely a bug in authentik.
{detail: 'Response returned an error code'}
runtime.ts:140 Uncaught (in promise) ResponseError: Response returned an error code
at bR.request (runtime.ts:140:15)
at async bR.rbacPermissionsAssignedByRolesAssignRaw (RbacApi.ts:587:26)
at async bR.rbacPermissionsAssignedByRolesAssign (RbacApi.ts:602:26)
```