Fix exception when requesting non existing trace point

(cherry picked from commit 7ac151a4)

console/console/trace_proxy.c

@@ -464,6 +464,7 @@ static void client_add(struct trace *client)
 	if (!trace) {
 		trace_free(client);
 		printf("Trace not found\n");
+		return;
 	}
 	
 	priv = trace->private;