Do not crash if friend whith no LC but show an error

coreapi/friend.c

@@ -108,13 +108,16 @@ static int friend_compare(const void * a, const void * b) {
 }
 
 static LinphoneFriendPresence * find_presence_model_for_uri_or_tel(const LinphoneFriend *lf, const char *uri_or_tel) {
-	bctbx_list_t *iterator = lf->presence_models;
-	LinphoneAddress *uri_or_tel_addr = linphone_core_interpret_url(lf->lc, uri_or_tel);
+	bctbx_list_t *iterator = NULL;
+	LinphoneAddress *uri_or_tel_addr = NULL;
 	LinphoneFriendPresence *result=NULL;
 	if (!lf->lc) {
 		ms_warning("Cannot find uri of tel [%s] from friend [%p] because not associated to any Linphone core object",uri_or_tel,lf);
 		return NULL;
 	}
+	iterator = lf->presence_models;
+	uri_or_tel_addr = linphone_core_interpret_url(lf->lc, uri_or_tel);
+
 	while (uri_or_tel_addr && iterator) {
 		LinphoneFriendPresence *lfp = (LinphoneFriendPresence *)bctbx_list_get_data(iterator);
 		LinphoneAddress *lfp_addr = linphone_core_interpret_url(lf->lc, lfp->uri_or_tel);

coreapi/friendlist.c

@@ -706,6 +706,7 @@ LinphoneFriend * linphone_friend_list_find_friend_by_uri(const LinphoneFriendLis
 LinphoneFriend * linphone_friend_list_find_friend_by_ref_key(const LinphoneFriendList *list, const char *ref_key) {
 	const bctbx_list_t *elem;
 	if (ref_key == NULL) return NULL;
+	if (list == NULL) return NULL;
 	for (elem = list->friends; elem != NULL; elem = bctbx_list_next(elem)) {
 		LinphoneFriend *lf = (LinphoneFriend *)bctbx_list_get_data(elem);
 		if ((lf->refkey != NULL) && (strcmp(lf->refkey, ref_key) == 0)) return lf;