A read zipper forked from a parent on a non-existent path is useless. There is no way the child zipper can ever explore anything but empty nothingness.
In the old API, that was a "so, what?" type of concern. But having to support fork_read_zipper always returning a valid zipper has upstream implications that are getting in the way of some optimizations for other zipper types that want to implement the ZipperForking trait.
A read zipper forked from a parent on a non-existent path is useless. There is no way the child zipper can ever explore anything but empty nothingness.
In the old API, that was a "so, what?" type of concern. But having to support
fork_read_zipperalways returning a valid zipper has upstream implications that are getting in the way of some optimizations for other zipper types that want to implement the ZipperForking trait.