Fix multiple gjs warnings and avoid crashing on refresh

Created by: rhertzog

I was so annoyed by the regular gnome-shell crashes triggered by this extension that I tried to debug and fix the issue myself. When I started on this, I noticed a few gjs warnings that I opted to fix first to clean up my view and better see real errors. But it turns out that once I fixed the warning about Gio.bus_watch_name() then I would no longer be able to reproduce the crash and the delay reported in #205 (closed) that I was also experiencing is gone.

Fixes #205 (closed), #198 (closed)