Javascript error: TypeError: Cannot read property 'success' of null

function offer() {
inlineAlert("", "Обработка торгового предложения - пожалуйста, подождите...");
$("#confirmModal").modal("hide");
var csv = "";
var sum = 0;
$("#right .slot").each(function(i, e) {
    csv += $(this).data("id") + ",";
    sum += $(this).data("price");
});
var turl = $("#tradeurl").val();
var remember = $("#remember").is(":checked") ? "on" : "off";
var url = "/withdraw_js";
if (DEPOSIT) {
    url = "/deposit_js";
}
$.ajax({
    "url": url,
    type: "GET",
    data: {
        "assetids": csv,
        "tradeurl": turl,
        "checksum": sum,
        "remember": remember
    },
    success: function(data) {
        alert(data);

в data передает null. Помогите понять почему. withdraw_js:

    case 'withdraw_js':
    if(!$user) exit(json_encode(array('success'=>false, 'error'=>'Вам необходимо авторизоватся на сайте чтобы продолжить.')));
    $items = array();
    $assetids = explode(',', $_GET['assetids']);
    $sum = 0;
    $prices = file_get_contents('prices.txt');
    $prices = json_decode($prices, true);
    $norm_itms = '';
    foreach ($assetids as $key) {
        if($key == "") continue;
        $sql = $db->query('SELECT * FROM `items` WHERE `id` = '.$db->quote($key));
        $row = $sql->fetch();
        $items[$row['botid']] = $row['market_hash_name'];
        $sum += $prices['response']['items'][$row['market_hash_name']]['value']*10;
        $norm_itms = $norm_itms.$row['market_hash_name'].',';
    }
    $out = array('success'=>false,'error'=>'');
    if(count($items) > 1) {
        $out = array('success'=>false,'error'=>'You choose more bots');
    } elseif($user['balance'] < $sum) {
        $out = array('success'=>false,'error'=>'Вам нужно больше монет!');
    } else {
        reset($items);
        $bot = key($items);
        $s = $db->query('SELECT `name` FROM `bots` WHERE `id` = '.$db->quote($bot));
        $r = $s->fetch();
        $db->exec('UPDATE `users` SET `balance` = `balance` - '.$sum.' WHERE `steamid` = '.$user['steamid']);
        $partner = extract_partner($_GET['tradeurl']);
        $token = extract_token($_GET['tradeurl']);
        $out = curl('http://'.$ip.':'.(3000+$bot).'/sendTradeMe/?names='.urlencode($norm_itms).'&partner='.$partner.'&token='.$token.'&checksum='.$_GET['checksum'].'&steamid='.$user['steamid']);
        $out = json_decode($out, true);
        if($out['success'] == false) {
            $db->exec('UPDATE `users` SET `balance` = `balance` + '.$sum.' WHERE `steamid` = '.$user['steamid']);
        } else {
            foreach ($assetids as $key) {
                $db->exec('DELETE FROM `items` WHERE `id` = '.$db->quote($key));
            }
            $out['bot'] = $r['name'];
            $db->exec('INSERT INTO `trades` SET `id` = '.$db->quote($out['tid']).', `bot_id` = '.$db->quote($bot).', `code` = '.$db->quote($out['code']).', `status` = 2, `user` = '.$db->quote($user['steamid']).', `summa` = '.'-'.$db->quote($_GET['checksum']).', `time` = '.$db->quote(time()));
        }
    }
    exit(json_encode($out));
    break;