Accessibility: tabindex=”-1″ missing in templates/popup.php

Hi there and out there
Not really help needed but a suggest.
To be compliant with accessibility concerns, you must add tabindex="-1" in templates/popup.php
First line should start with <div tabindex="-1" id="pum-<?php pum_popup_ID(); ?>"...
instead of <div id="pum-<?php pum_popup_ID(); ?>"...

Source: https://webaim.org/techniques/keyboard/tabindex (open in a new window)
Or maybe have I missed something in the settings?

Regards