avoid seg in invalid presence payload

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10483 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/endpoints/mod_sofia/sofia_presence.c

@@ -1611,7 +1611,7 @@ void sofia_presence_handle_sip_i_publish(nua_t *nua, sofia_profile_t *profile, n
 					note_txt = note->txt;
 				}
 
-				if (person && (act = switch_xml_child(person, "rpid:activities"))) {
+				if (person && (act = switch_xml_child(person, "rpid:activities")) && act->child && act->child->name) {
 					if ((rpid = strchr(act->child->name, ':'))) {
 						rpid++;
 					} else {