Как установить заголовок ответа HTTP в PHP для JavaScript Fetch API

Question

Я пытаюсь установить http_response_code(); в PHP, чтобы запустить if-statement в ответе fetch API. Но response.status в JavaScript всегда 200 OK. Я действительно застрял с этим.

Что я делаю не так?

Вот бит JavaScript:

    fetch(url, {
      method: 'POST',
      body: formData
    })
      .then(response => {
        if (response.status === 422) {
          console.log(
            'The upload did not work. Please make sure your files are images and no bigger than 2MB.'
          );
        }
      })
      .catch(error => {
        console.log('Error: ', error);
      });
  }

И в PHP:

if ($_SERVER['REQUEST_METHOD'] === 'POST' ) {

    if (isset($_POST['folder'])) {
        $folder = $_POST['folder'];
    } else {
        $folder = 'new-folder';
    }

    if (isset($_FILES['files'])) {

        $errors = [];
        $path = $_SERVER['DOCUMENT_ROOT'] . '/data/uploads/images/' . $folder . "/";

        // if folder does not exist, create it
        if (!file_exists($path)) {
            mkdir($path, 0777, true);
        } else {
            // stuff
        }

        $extensions = ['jpg', 'jpeg', 'png', 'gif', 'webp'];
        $pattern = "#^(image/)[^\s\n<]+$#i";
        $all_files = count($_FILES['files']['tmp_name']);

        for ($i = 0; $i < $all_files; $i++) {
            $file_name = $_FILES['files']['name'][$i];
            $file_tmp = $_FILES['files']['tmp_name'][$i];
            $file_type = $_FILES['files']['type'][$i];
            $file_size = $_FILES['files']['size'][$i];
            $tmp = explode('.', $_FILES['files']['name'][$i]);
            $file_ext = strtolower(end($tmp));
            $file = $path . $file_name;
            $verifyimg = getimagesize($_FILES['files']['tmp_name'][$i]);

            try {

                if(!preg_match($pattern, $verifyimg['mime'])) {
                    throw new Exception("Only image files are allowed!");
                }

              // here goes more validation like this

                if (empty($errors)) {
                    move_uploaded_file($file_tmp, $file);
                }

            } catch (Exception $exception) {
                echo $exception->getMessage();

                // Get the current response code and set a new one
                http_response_code(422);

                // Get the new response code
                http_response_code();
            }
        }
    }
}