This issue occurs when closing the DB Navigator, when the "Close when last session window closes" option in preferences is ticked.
Steps to reproduce:
- In Preferences | General | Session, ensure "Close when last session window closes" is ticked. Also ensure "Show Code Editor after connection" is deselected.
- Still in preferences, go into Project Manager and only leave "Hide inactive project windows" and "On Connect" ticked and apply settings.
- In Project Manager window, open a connection.
- Close the DB Navigator window with small blue exit arrow on top right: The error appears in the Output window.