fix uuid_jitterbuffer edge case debugging a non-existant jb causing a seg

src/mod/endpoints/mod_sofia/mod_sofia.c

@@ -1366,7 +1366,7 @@ static switch_status_t sofia_receive_message(switch_core_session_t *session, swi
 						if (s && !strcmp(s, "off")) {
 							s = NULL;
 						}
-						switch_rtp_debug_jitter_buffer(tech_pvt->rtp_session, s);
+						status = switch_rtp_debug_jitter_buffer(tech_pvt->rtp_session, s);
 						goto end;
 					}
 

src/switch_rtp.c

@@ -1875,7 +1875,7 @@ static void jb_logger(const char *file, const char *func, int line, int level, c
 SWITCH_DECLARE(switch_status_t) switch_rtp_debug_jitter_buffer(switch_rtp_t *rtp_session, const char *name)
 {
 
-	if (!switch_rtp_ready(rtp_session)) {
+	if (!switch_rtp_ready(rtp_session) || !rtp_session->jb) {
 		return SWITCH_STATUS_FALSE;
 	}