querystring.parse: handle undefined value properly

lib/querystring.js

@@ -77,6 +77,7 @@ var chunks = /(?:(?:^|\.)([^\[\(\.]+)(?=\[|\.|$|\()|\[([^"'][^\]]*?)\]|\["([^\]"
 // Parse a key=val string.
 QueryString.parse = QueryString.decode = function (qs, sep, eq) {
   var obj = {};
+  if (qs === undefined) { return {} }
   String(qs).split(sep || "&").map(function (keyValue) {
     var res = obj,
       next,

test/simple/test-querystring.js

@@ -165,3 +165,6 @@ var f = qs.stringify({
   }, ";", ":")
 }, ";", ":");
 assert.equal(f, "a:b;q:x%3Ay%3By%3Az");
+
+
+assert.deepEqual({}, qs.parse());