Is it possible to add a window that will ask which fields it wants to keep?

Side question: How does this add-on affect the scheduling information?

Addon drops error "invalid configuration" and anki freezes with following configuration:

Version ⁨2.1.54 (b6a7760c)⁩
Python 3.9.7 Qt 6.3.1 PyQt 6.3.1

I used Addon with earlier versions of Anki sucessfully.
Regards, Philipp

Error
An error occurred. Please start Anki while holding down the shift key, which will temporarily disable the add-ons you have installed.
If the issue only occurs when add-ons are enabled, please use the Tools > Add-ons menu item to disable some add-ons and restart Anki, repeating until you discover the add-on that is causing the problem.
When you've discovered the add-on that is causing the problem, please report the issue to the add-on author.
Debug info:
Anki 2.1.54 (b6a7760c) Python 3.9.7 Qt 5.14.1 PyQt 5.14.1
Platform: Mac 12.6
Flags: frz=True ao=True sv=3
Add-ons, last update check: 2022-09-29 14:25:09
Add-ons possibly involved: ⁨Merge duplicate notes⁩

Caught exception:
Traceback (most recent call last):
File "/Users/AndrewHerson 1/Library/Application Support/Anki2/addons21/55394168/init.py", line 30, in merge_duplicates
mode = config.get("merge_mode", "longer")
AttributeError: 'NoneType' object has no attribute 'get'