PasswordException in closure

src/util.js

@@ -58,14 +58,19 @@ function shadow(obj, prop, value) {
   return value;
 }
 
+var PasswordException = (function PasswordExceptionClosure() {
   function PasswordException(msg, code) {
     this.name = 'PasswordException';
     this.message = msg;
     this.code = code;
   }
+
   PasswordException.prototype = new Error();
   PasswordException.constructor = PasswordException;
 
+  return PasswordException;
+})();
+
 function bytesToString(bytes) {
   var str = '';
   var length = bytes.length;