…#19453)

Fixes #19443. This case is too niche (and should be trivially
avoidable), so just not crashing should be good enough. The value is
indeed redefined, and trying to massage the plugin to move the
`X-redefinition` back to `X` in names is not worth the effort IMO.

Fixes #19425. That property has no setter so it should safe to exclude.
It can raise in inconsistent state that arises when it is not copied
last?

Current version replaces `None` (which indicates "no items") with an
empty union (=`Uninhabited`). This breaks inference in some cases.

Fixes #19483.