[modules] Improve error messages.

test/message/modules-skip-cycle3.js

Index: test/message/modules-skip-cycle3.js
diff --git a/test/message/arrow-invalid-rest.js b/test/message/modules-skip-cycle3.js
similarity index 66%
copy from test/message/arrow-invalid-rest.js
copy to test/message/modules-skip-cycle3.js
index 870dbe9f542ea95050514227feaf9b2299ca516d..a63a660c16d0c7ca6a974c435c80460462beb47e 100644
--- a/test/message/arrow-invalid-rest.js
+++ b/test/message/modules-skip-cycle3.js
@@ -1,8 +1,6 @@
 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-//
-//
 
-var f = (...x = 10) => x;
-f(1, 2, 3, 4, 5);
+export {y as a} from "modules-cycle3.js";
+export {x as b} from "modules-cycle3.js";