Fix issues with out of sync stalist

src/cntlr.c

@@ -640,6 +640,9 @@ static void cntlr_get_all_sta_metrics(struct controller *c)
 	list_for_each_entry(n, &c->nodelist, list) {
 		struct sta *s = NULL;
 
+		if (!n->sta_count || list_empty(&n->stalist))
+			continue;
+
 		list_for_each_entry(s, &n->stalist, list) {
 			struct cmdu_buff *cmdu;