PDF generation in a custom action

Hey. Months ago I had a custom action that generated a pdf based on some db results working. But it has stopped working. I'm getting

'TypeError: byte_order.ByteOrder is undefined'

What has changed??

 final pdf = pw.Document();

  // ... PDF generation stuff....

  print('file generated');

BREAKS FROM HERE....

  // Generate PDF bytes

  final bytes = await pdf.save();

  // Create blob from bytes

  final blob = html.Blob([bytes], 'application/pdf');

  print('blob  genrated');

  // Create download URL

  final url = html.Url.createObjectUrlFromBlob(blob);

  print('url genrated');

  // Create anchor element for download

  final anchor = html.AnchorElement()

    ..href = url

    ..download = 'order_labels.pdf' // This will be the downloaded file name

    ..style.display = 'none';