url_prefix option gives ERROR with _default app

[nicozanf]

It gives "IndexError: string index out of range". It occurs on the _default app only.

With the command:

./py4web.py run apps -U /dev

[....]

[ ] loading _default ...
[2024-07-16T22:50:52.658092]: Traceback (most recent call last):
File "/home/nico/py4web/py4web/core.py", line 1430, in import_app
module = load_module(module_name, init)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nico/py4web/py4web/core.py", line 157, in load_module
spec.loader.exec_module(module)
File "", line 995, in exec_module
File "", line 488, in _call_with_frames_removed
File "/home/nico/py4web/apps/_default/init.py", line 5, in
@action("index")
^^^^^^^^^^^^^^^
File "/home/nico/py4web/py4web/core.py", line 1082, in call
Reloader.register_route(app_name, short_path, self.kwargs, func)
File "/home/nico/py4web/py4web/core.py", line 1485, in register_route
bottle.route(rule, **kwargs)(dec_func)
File "/home/nico/py4web/venv/lib/python3.12/site-packages/ombott/ombott.py", line 138, in decorator
self.add_route(rule, method, callback, name, overwrite=overwrite)
File "/home/nico/py4web/venv/lib/python3.12/site-packages/ombott/ombott.py", line 130, in add_route
return self.router.add(rule, method, handler, name, overwrite=overwrite)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nico/py4web/venv/lib/python3.12/site-packages/ombott/router/radirouter.py", line 240, in add
return self._add(rule, methods, handler, name, meta=meta, overwrite=overwrite)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nico/py4web/venv/lib/python3.12/site-packages/ombott/router/radirouter.py", line 375, in _add
route = Route(rule)
^^^^^^^^^^^
File "/home/nico/py4web/venv/lib/python3.12/site-packages/ombott/router/radirouter.py", line 55, in init
pattern, params, filters, pattern_out, filters_out = self.class.parse_rule(rule)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nico/py4web/venv/lib/python3.12/site-packages/ombott/router/radirouter.py", line 177, in parse_rule
assert rule[0] == '/'
~~~~^^^
IndexError: string index out of range
[FAILED] loading _default (string index out of range)
[X] loaded _documentation
Dashboard is at: http://127.0.0.1:8000/_dashboard
Ombott v2.0 server starting up (using <class 'py4web.server_adapters.rocketServer..RocketServer'>(reloader=False, logging_level=30))...
Listening on http://127.0.0.1:8000/
Hit Ctrl-C to quit.

[nicozanf]

Strangely, using --url-prefix=/dev gives exactly the same error, while -U=/dev gives a lot more errors (with click module, also) and py4web does not even start