fix: show error name the error stack for Node.js 8

Author: luin

lib/reply_error.js

@@ -1,9 +1,16 @@
 'use strict';
 
-module.exports = function ReplyError(message) {
-  Error.captureStackTrace(this, this.constructor);
+var util = require('util');
+
+function ReplyError(message) {
   this.name = this.constructor.name;
-  this.message = message;
+  this.message = message || '';
+
+  if (Error.captureStackTrace) {
+    Error.captureStackTrace(this, this.constructor);
+  }
 };
 
-require('util').inherits(module.exports, Error);
+util.inherits(ReplyError, Error);
+
+module.exports = ReplyError;