Removing a site from the list of sites shows new blank tab

[alisterscott]

Steps to Reproduce

1. Enable the add on with at least one site
2. Expand the site details and click "Remove yousite.blog"

What I expected

Modal asking if I want to remove site

What happened instead

A blank new tab is opened and focused. The URL was https://n-iuogkxbn2sa775flbhawthhj7aunrmf3qvds76a-0lu-script.googleusercontent.com/userCodeAppPanel#

Video