TpGroupMixin: if flags allow adding or removing a member, but the callback is NULL, raise error rather than segfaulting
TpGroupMixin: if flags allow adding or removing a member, but the callback is NULL, raise error rather than segfaulting

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib