Crash on Xcode beta 4, but not with beta 3

The last line of this function crashes. When going back to beta 3, no crash.

    func configuredOutlineHeaderCell(textStyle: UIFont.TextStyle) -> UICollectionView.CellRegistration<UICollectionViewListCell, String> {

        return UICollectionView.CellRegistration<UICollectionViewListCell, String> { (cell, indexPath, title) in

            var content = cell.defaultContentConfiguration()

            content.text = title

            content.textProperties.font = UIFont.preferredFont(forTextStyle: textStyle)

            cell.contentConfiguration = content

            cell.accessories = [.outlineDisclosure(options: .init(style: .header))]// DEBUG Aug 11 beta 4 crashing

        }

    }