Request failed for http://services.runescape.com/m=itemdb_rs/api/catalogue/detail.json?item=undefined returned

var address = 'ip';
var user = 'user';
var userPwd = 'pw';
var db = 'db';

var dbUrl = 'jdbc:mysql://' + address + '/' + db;

function getJSON(id) {

  var url = "http://services.runescape.com/m=itemdb_rs/api/catalogue/detail.json?item=" + id;
  var response = UrlFetchApp.fetch(url); // get api endpoint
  var json = response.getContentText(); // get the response content as text
  var data = JSON.parse(json)

  var conn = Jdbc.getConnection(dbUrl, user, userPwd);

  var stmt = conn.prepareStatement('INSERT INTO items '
      + '(name, description, itemid, img) values (?, ?, ?, ?)');
  stmt.setString(1,data.item.name);
  stmt.setString(2, data.item.description);
  stmt.setString(3,data.item.id);
  stmt.setString(4, data.item.icon);
  stmt.execute();
}

for(var i = 0; i < 50000; i++){
  try{
    Utilities.sleep(6000);
    getJSON(i);
  } catch(e) {
    i++;
  }
}