Fix indexer position in main, check if stacks is well mallocked before index stack

main.c

@@ -24,9 +24,9 @@ static int	push_swap(char **tab, int len, int mod)
 	if (mod == -1)
 		return (0);
 	stacks = init_stacks(len, tab, mod);
-	indexer(stacks);
 	if (!stacks)
 		return (0);
+	indexer(stacks);
 	if (check_order(stacks->a))
 	{
 		free_all(stacks);