document portal: Report right error for setattr
document portal: Report right error for setattr

flatpak/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,flatpak/flatpak,flatpak/flatpak,GeorgesStavracas/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,flatpak/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,handsome-feng/flatpak,flatpak/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak