pyedifice error (failed assertion)

[jamesdbrock]

This gets written to the console and the program hangs:

Exception in callback App._defer_rerender.<locals>.rerender_callback() at /nix/store/5p5w586v2gr5zmf0g94iwrka60mbwn4g-python3-3.10.13-env/lib/python3.10/site-packages/edifice/app.py:199
handle: <Handle App._defer_rerender.<locals>.rerender_callback() at /nix/store/5p5w586v2gr5zmf0g94iwrka60mbwn4g-python3-3.10.13-env/lib/python3.10/site-packages/edifice/app.py:199>
Traceback (most recent call last):
  File "/nix/store/s6fgyqbk8vn1014daznm5kqx90xdn86x-python3-3.10.13/lib/python3.10/asyncio/events.py", line 80, in _run
    self._context.run(self._callback, *self._args)
  File "/nix/store/5p5w586v2gr5zmf0g94iwrka60mbwn4g-python3-3.10.13-env/lib/python3.10/site-packages/edifice/app.py", line 202, in rerender_callback
    self._request_rerender(list(els), {})
  File "/nix/store/5p5w586v2gr5zmf0g94iwrka60mbwn4g-python3-3.10.13-env/lib/python3.10/site-packages/edifice/app.py", line 233, in _request_rerender
    render_result.run()
  File "/nix/store/5p5w586v2gr5zmf0g94iwrka60mbwn4g-python3-3.10.13-env/lib/python3.10/site-packages/edifice/engine.py", line 301, in run
    command.fn(*command.args, **command.kwargs)
  File "/nix/store/5p5w586v2gr5zmf0g94iwrka60mbwn4g-python3-3.10.13-env/lib/python3.10/site-packages/edifice/base_components/base_components.py", line 1682, in _set_on_change
    assert self.underlying is not None
AssertionError

This gets written to the label (truncated):

/home/...
[Errno 2] No such file or directory: '/home/...'

I think we should try to ensure that edifice crashes in a more graceful way.