Role deletion shows "Data Not Found (400)." page when it is associated with some another role

Role deletion shows "Data Not Found (400)." page when it is associated with some another role.

Steps to reproduce:

1. Create Role say role1.
2. Create another Role say role2 and associated role1 to it.
3. Now try deleting the role1, we would get "Data Not Found (400)." page. We should get alert stating "Role 'role1' can not be deleted as it is referenced in one or more other roles".

Snapshot is attached for reference.