protected function checkError()
	{
		if (isset($_GET[$this->errorParam])) {
			$error_code = $_GET[$this->errorParam];
			if ($error_code === $this->errorAccessDeniedCode) {
				// access_denied error (user canceled)
				$this->cancel();
			} else {
				$error = $error_code;
				if (isset($_GET[$this->errorDescriptionParam])) {
					$error = $_GET[$this->errorDescriptionParam] . ' (' . $error . ')';
				}
				throw new ErrorException($error);
			}
			return false;
		}

		return true;
	}