Sentinel in namespace path breaks NamespaceReader
Bug report
Bug description:
As reported in python/importlib_resources#311 and highlighted by python/importlib_resources#318, when an editable install adds a sentinel value to a namespace path, it can break the NamespaceReader when that value doesn't resolve to a pathlib.Path or zipfile.Path.
This code was introduced in #106531 and fixed in importlib_resources 6.4.5.
CPython versions tested on:
3.13
Operating systems tested on:
macOS