Summary: Fixes T10317. If we failed to load `$device`, it will be null, so we won't be able to call `getName()` on it.
Test Plan: `SSH_CLIENT='127.0.0.1' ./bin/ssh-exec --phabricator-ssh-device xyz` no longer fatals
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10317
Differential Revision: https://secure.phabricator.com/D15235
3f920d8904