Fixes crash when no panorama wallpapers are found.
Fixes crash when no panorama wallpapers are found.

Fixes: NB#149520 - Hildon Home crashes when change background

community-ssu/hildon-home,Cordia/hildon-home,Cordia/hildon-home,Cordia/hildon-home,community-ssu/hildon-home,community-ssu/hildon-home