[gsettings] Do not crash when converting a schema with unknown types
[gsettings] Do not crash when converting a schema with unknown types

Distrotech/GConf,GNOME/gconf,Distrotech/GConf,hyperair/gconf-gdbus,hyperair/gconf-gdbus,GNOME/gconf,Distrotech/GConf,hyperair/gconf-gdbus,GNOME/gconf,hyperair/gconf-gdbus,Distrotech/GConf,GNOME/gconf