container: Stop ignoring notifies if ->add_child fails
container: Stop ignoring notifies if ->add_child fails

cfoch/gst-editing-services,cfoch/ges,cfoch/ges,cfoch/ges,pitivi/gst-editing-services,pitivi/gst-editing-services,cfoch/gst-editing-services,pitivi/gst-editing-services,cfoch/gst-editing-services,cfoch/gst-editing-services,cfoch/ges,pitivi/gst-editing-services