Hi, I'm currently have the same problem.
I don't know why is a requirement a Tab. In my module I'm not defining an administration tab, just the "configure" link.
The only thing why it is needed is to put a default image, where? I don't know, seems as an icon beside title as seen in
admin/themes/default/template/helpers/options/options.tpl file.....
but wait!! in tutorials appear this
['image'] => 'url to icon', // If missing, will use the default icon for the tab.
This is bad, because "image" is optional (between brackets), but still need a Tab value to create default image (here: https://github.com/PrestaShop/PrestaShop/blob/1.6/classes/helper/HelperOptions.php#L61 ) when in this case there is no Tab for module ($tab = false), just a simply "configure" link
Hope someone can help this, seems need to write right path to a non-module default icon image.
Thanks in advance