[tag:bug]

I found the exact error which I faced:

> cannot read property 0 or null

on this line when the script tries to attach custom DOM elements:

     site_options += '<option ' + selected + ' value="' + value.site + '">Show Only ' + value.site[0].toUpperCase() + value.site.substr(1) + '</option>';
 And fixed that to check null before this line:

    if(value.site != null)
    site_options += '<option ' + selected + ' value="' + value.site + '">Show Only ' + value.site[0].toUpperCase() + value.site.substr(1) + '</option>';

Now it works.