usb-protection: don't crash when screensaver service is unavailable
gnome_settings_bus_get_screen_saver_proxy() can return NULL, e.g. when D-Bus is broken. We need to handle that case.
Fixes #585 (closed)
gnome_settings_bus_get_screen_saver_proxy() can return NULL, e.g. when D-Bus is broken. We need to handle that case.
Fixes #585 (closed)