tracker-extract: Check for return value in GStreamer extractor
tracker-extract: Check for return value in GStreamer extractor

outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker