Wrong error message when renaming or moving files

Since upgrading to NC 18.0.1 I get an error message popup (top right corner) when renaming/moving files saying "Cannot rename/move ". When reloading the page the new filename is correctly renamed/moved.
In the log i see something like this:

Undefined variable: node at /var/www/nextcloud/apps/workflow_script/lib/Operation.php#203
Error: Call to a member function getPath() on null

Thank you for any kind of help,

Well, if it is a new error with the upgrade, then the bugtracker for workflow script could be an option: https://github.com/nextcloud/workflow_script/issues

I have inserted an issue for this:

This seems to be related to external scripts with the “Workflow external scripts apps”. I had a test script active and the issue went away by deleting my external script from the workflows.