Aggregation in views causes ajax error

Please provide the steps to reproduce the bug.

Inserted the steps and corrected the patch

Please include details of the Ajax error in the issue summary.

inserted error reports

Thank you for reporting. Tagging for a test case to be added

Not only the count aggregation type causes the error but all but the default "group" one.
All types of aggregation produce the same error.
The error is also present in drupal 9.5.x and has already been reported.
The basic problem is that by setting a grouping type other than the default "group" the form for selecting the columns does not appear upon subsequent modifications.
The proposed patch does not solve the main problem, but it allows you to work on your vision and not lose all the work done.
I haven't found any problems that the patch can cause.
I'm looking for the cause of the main problem but I don't know the module enough, it could also depend on the views_ui module

I found the main problem!
The EntityField class which extends FieldPluginBase which extends HandlerBase is used to submit the form.
The NumericField class which extends FieldPluginBase which extends HandlerBase is used in the construction of the form.
The definition of the group_column and group_columns fields occurs in the EntityField class which is not called when constructing the form.
Proposed solution:
In the ConfigHandlerGroup->buildForm class of the views_ui module, ensure that in this case EntityField is called as handler instead of NumericField.
I ask for confirmation from those who know these two modules better.

The path ensures that the same handler is used both for building and sending the form.

corrected error detected

As pointed out in #10, this is a duplicate of 🐛 Ajax error on views with aggregation Postponed: needs info , so closing this one so we can focus our efforts to fix this in one spot.