Versions are not meant to be trashed. Currently there's nothing preventing user to do that. Or we can get a trashed version with help of automatic versioning when editing a trashed document (which shouldn't be allowed).
In the end, trash migrator fails to migrate trashed version because property is not allowed to be overridden.
We want to fix the migrator before fixing other aspect leading to this state.
In the end don't migrate trashed version.