gst-launch: Handle taglist copy failure
gst-launch: Handle taglist copy failure

If we couldn't copy the tags, just return instead of trying to use bogus
values.

Lachann/gstreamer,shelsonjava/gstreamer,cfoch/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,ensonic/gstreamer,jpxiong/gstreamer,mparis/gstreamer,cfoch/gstreamer,Lachann/gstreamer,ensonic/gstreamer,cfoch/gstreamer,jpakkane/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,centricular/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,cfoch/gstreamer,surround-io/gstreamer,centricular/gstreamer,mparis/gstreamer,Lachann/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,centricular/gstreamer,mparis/gstreamer,ensonic/gstreamer,krichter722/gstreamer,jpakkane/gstreamer,mparis/gstreamer,ensonic/gstreamer,krichter722/gstreamer,jpakkane/gstreamer,jpakkane/gstreamer,centricular/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,Lachann/gstreamer,mparis/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,cfoch/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,cablelabs/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,shelsonjava/gstreamer,StreamUtils/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,ensonic/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,surround-io/gstreamer,centricular/gstreamer