private function imageError($file, $firsttime, $msg)
	{
		$this->failedImages[$file] = true;

		if ($firsttime && ($this->mpdf->showImageErrors || $this->mpdf->debug)) {
			throw new \Mpdf\MpdfImageException(sprintf('%s (%s)', $msg, $file));
		}

		$this->logger->warning(sprintf('%s (%s)', $msg, $file), ['context' => LogContext::IMAGES]);
	}