来自Google Closure编译文件的TypeError

我有一个使用Google Closure编译器编译的Javascript文件，该错误提示我TypeError: f is undefined。当我查看编译后的代码时，无法理解，但其中的大部分被注释掉了。我真的很困惑为什么会收到此错误，但我怀疑它与以下脚本有关（这是自收到此错误以来我唯一编辑的内容）。

var response;

var request = new goog.net.XhrIo();

goog.events.listen(request, "complete", function(){

    if (request.isSuccess()) {

        response = request.getResponseText();

        console.log("Satus code: ", request.getStatus(), " - ", request.getStatusText());

    } else {

        console.log(
        "Something went wrong in the ajax call. Error code: ", request.getLastErrorCode(),
        " - message: ", request.getLastError()
        );
    }

});


request.send("load_vocab.php");


var rawVocab = response[rawVocab];
var optionVocab = response[optionVocab];
alert(rawVocab.length);
alert(optionVocab.length);

这也是load_vocab.php ...

try {
    $conn = new PDO('mysql:host=localhost;dbname=tygrif_school', $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $stmt = $conn->prepare('SELECT word, translation, example_sentence_1 FROM vocabulary_game WHERE game_type = :game_type');
    $stmt->execute(array('game_type' => 'target'));

    while ($row = $stmt->fetch(PDO::FETCH_OBJ)) {
       $data['rawVocab'][] = $row;
    }

    $stmt = $conn->prepare('SELECT word, translation FROM vocabulary_game');
    $stmt->execute(array());

    while ($row = $stmt->fetch(PDO::FETCH_OBJ)) {
        $data['optionVocab'][] = $row;
    }
} catch(PDOException $e) {
    echo 'ERROR: ' . $e->getMessage();
}

echo json_encode($data);