fix segfault.

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3921 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/endpoints/mod_sofia/mod_sofia.c

@@ -2732,7 +2732,7 @@ static void sip_i_state(int status,
 		}
 		break;
 	case nua_callstate_ready:
-		if (nh == tech_pvt->nh2) {
+		if (tech_pvt && nh == tech_pvt->nh2) {
 			switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG, "Cheater Reinvite!\n");
 			switch_set_flag_locked(tech_pvt, TFLAG_REINVITE);
 			tech_pvt->nh = tech_pvt->nh2;