Merge pull request #1475 from carsonmcdonald/fixparseerror

Return when block argument error

src/parse.y

@@ -857,6 +857,7 @@ ret_args(parser_state *p, node *n)
 {
   if (n->cdr) {
     yyerror(p, "block argument should not be given");
+    return NULL;
   }
   if (!n->car->cdr) return n->car->car;
   return new_array(p, n->car);