You are correct. If you would like to test a minor upgrade that corrects this, please replace your current DenominoViso.py file with the attached one. And report back if it appears to correct your issue.
Since you did not mention the platform you are running on, I can only give you a hint where to find the file for replacement. On Windows it is usually at c:\Users\you\AppData\Roaming\gramps42\plugins\DenominoViso or similar. On Linux /home/you/.gramps/gramps42/plugins/DenominoViso or similar.