[modules] Improve error messages.

test/mjsunit/modules-fail-5.js

Index: test/mjsunit/modules-fail-5.js
diff --git a/test/mjsunit/modules-fail-5.js b/test/mjsunit/modules-fail-5.js
deleted file mode 100644
index 046275b2d34752a8a95e55f567ada10aea8d3c87..0000000000000000000000000000000000000000
--- a/test/mjsunit/modules-fail-5.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// 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.
-//
-// MODULE
-
-import {a as b} from "modules-fail-5.js";
-export {c as a} from "modules-fail-5.js";
-import {c} from "modules-fail-5.js";