@Jonathan I’m guessing you issued the command:
./deploy.sh staging staging.hthroots.com
Given your site name hthroots.com, try this command instead:
./deploy.sh staging hthroots.com
The dict object (“dictionary”) in the error message is wordpress_sites. In your case, one item in that list of wordpress_sites falls under the header (“attribute”) hthroots.com, but none falls under the header staging.hthroots.com.
I realize it could be confusing. Although the README says that this command parameter is <site_name>, the docs currently say <domain>. This latter might make you think to add the staging part of the domain name. The idea, however, is that domain refers to the domain of the overall project (hthroots.com), for which there are multiple environments (development, staging, production).