cleanly call Stream.set_state during shutdown

gstlal-inspiral/bin/gstlal_inspiral

@@ -1092,10 +1092,14 @@ for output_file_number, (svd_bank_url_dict, output_url, ranking_stat_output_url,
 	print("shutdown: del banks", flush=True, file=sys.stderr)
 	del banks
 
+	# FIXME: shutdown in response to error conditions is still an area that needs attention
+	#        or at least documentation/notes. 
 	print("shutdown: Gstreamer set state to NULL", flush=True, file=sys.stderr)
 	if stream is not None:
-	   if stream.get_state() is not Gst.State.NULL:
-	      stream.set_state(Gst.State.NULL)
+		try:
+			stream.set_state(Gst.State.NULL)
+		except RuntimeError as e:
+			print("shutdown: RuntimeError setting stream state to NULL: %s" % repr(e), flush=True, file=sys.stderr)
 
 
 #