What is the bug?

The user creation screen allows a user to continue to add backend roles even if no text is entered. In addition to creating blank roles, the remove button is always enabled even if no text is entered. If there is only one backend role, the remove button will blank out the text that has been filled. If there is more than one role then remove will remove the entire row.

Blank backend roles do show up for the logged in user with a blank backend role:

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Go to Security -> Internal Users
2. Create a User
3. Click on Add another backend role

What is the expected behavior?

The backend role should not be blank before a new one can be added

Tested on 2.5.0