don't printf null

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@6411 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/endpoints/mod_sofia/sofia_glue.c

@@ -1112,7 +1112,7 @@ switch_status_t sofia_glue_activate_rtp(private_object_t *tech_pvt, switch_rtp_f
 			}
 		}
 	} else {
-		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "RTP REPORTS ERROR: [%s]\n", err);
+		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "RTP REPORTS ERROR: [%s]\n", switch_str_nil(err));
 		switch_channel_hangup(tech_pvt->channel, SWITCH_CAUSE_DESTINATION_OUT_OF_ORDER);
 		switch_clear_flag_locked(tech_pvt, TFLAG_IO);
 		return SWITCH_STATUS_FALSE;