Unable to convert MS Word DOCX document to DOC format (NullReferenceException)

I have an issue converting the attached document from *.docx to doc format.
There is an exception:

System.NullReferenceException
  HResult=0x80004003
  Message=Object reference not set to an instance of an object.
  Source=Aspose.Words

Code sample:

var doc = new Document(inputFile);
doc.Save("document.doc");

I use Aspose.Words.dll 25.2.0.0.
test2.zip (16.2 KB)

@licenses
We have opened the following new ticket(s) in our internal issue tracking system and will deliver their fixes according to the terms mentioned in Free Support Policies.

Issue ID(s): WORDSNET-27889

You can obtain Paid Support Services if you need support on a priority basis, along with the direct access to our Paid Support management team.

The issues you have found earlier (filed as WORDSNET-27889) have been fixed in this Aspose.Words for .NET 25.4 update also available on NuGet.