VM118: 1 неперехваченная ошибка синтаксиса: неожиданный токен <в JSON в позиции

Question

public function follow($followerID, $user_id){
    $this->create('follow', array('sender' => $user_id, 'receiver'=> $followID, 'followOn'=> date("Y:M:D H:i:s")));
    $this->addFollowCount($followID, $user_id);
    $stmt=$this->pdo->prepare('SELECT * FROM `users` WHERE `user_id` =:followID');
    $stmt->execute(array("followID" => $followID));
    $data = $stmt->fetch(PDO::FETCH_ASSOC);
    echo json_encode($data);
}
public function unfollow($followerID, $user_id){
    $this->delete('follow', array('sender' => $user_id, 'receiver'=> $followID));
    $this->addFollowCount($followID, $user_id);
    $stmt=$this->pdo->prepare('SELECT * FROM `users` WHERE `user_id` =:followID');
    $stmt->execute(array("followID" => $followID));
    $data = $stmt->fetch(PDO::FETCH_ASSOC);
    echo json_encode($data);
}

public function addFollowCount($followerID, $user_id){
    $stmt = $this->pdo->prepare("UPDATE `users` SET `following` = `following` + 1 WHERE `user_id` = :user_id; UPDATE `users` SET `followers` = `followers`+ 1 WHERE  `user_id`= :followID ");
    $stmt->execute(array("user_id" => $user_id, "followID" => $followID));  
}
public function removeFollowCount($followerID, $user_id){
    $stmt = $this->pdo->prepare("UPDATE `users` SET `following` = `following` - 1 WHERE `user_id` = :user_id; UPDATE `users` SET `followers` = `followers`- 1 WHERE  `user_id`= :followID ");
    $stmt->execute(array("user_id" => $user_id, "followID" => $followID));  
}

Вот мой код AJAX:

 if (isset($_POST['unfollow']) && !empty($_POST['unfollow'])) {
    $user_id = $_SESSION['user_id'];
    $followID = $_POST['unfollow'];
    $getFromU->unfollow($followID, $user_id);

}
if (isset($_POST['follow']) && !empty($_POST['follow'])) {
    $user_id = $_SESSION['user_id'];
    $followID = $_POST['follow'];
    $getFromU->follow($followID, $user_id);

}

VM262: 1 Uncaught SyntaxError: Неожиданный токен <в JSON в позиции 0 в JSON.parse () <br> в Object.success (follow.js: 7)
в j (jquery.min.js: 2)
в Object.fireWith [as resolWith] (jquery.min.js: 2)
в точке x (jquery.min.js: 4)
в XMLHttpRequest.b (jquery.min.js: 4)

где я ошибаюсь и использую jquery.min.js lib1.1