fix code serialisation bug

lib/6to5/transform.js

@@ -6,6 +6,7 @@ var _        = require("lodash");
 
 var transform = module.exports = function (code, opts) {
   opts = opts || {};
+  code = (code || "") + "";
 
   _.defaults(opts, {
     sourceMapObject: false,

package.json

@@ -1,7 +1,7 @@
 {
   "name": "6to5",
   "description": "Turn ES6 code into vanilla ES5 with no runtime required",
-  "version": "0.0.3",
+  "version": "0.0.4",
   "repository": {
     "type": "git",
     "url": "https://github.com/sebmck/6to5.git"