public function updateTaskErrorMessage($id = null, $errorMessage = null, $keepExistingMessage = false) {
		if (empty($id) || !$this->exists($id) || empty($errorMessage)) {
			return false;
		}

		if ($keepExistingMessage) {
			$this->id = $id;
			$message = $this->field('failure_message');
			if (!empty($message)) {
				$errorMessage = $message . "\n" . $errorMessage;
			}
		}

		return $this->markJobFailed($id, $errorMessage);
	}