Traceback in log with custom error page

[davetapley]

Not sure if by design, but if you run the example for a custom error page you will still get a traceback in the log:

Traceback (most recent call last):
  File "/workspaces/ng/.venv/lib/python3.12/site-packages/nicegui/page.py", line 146, in decorated
    result = func(*dec_args, **dec_kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "error.py", line 17, in raise_timeout_error
    raise TimeoutError('This took too long')
TimeoutError: This took too long
This took too long
NoneType: None

It happened in my app and I was confused for a few moments, I feel like having an on_page_exception should count as 'catching' the exception (especially since you can re-raise within the custom page)?

[falkoschindler]

Hi @davetapley,

The current behavior is by design. The NiceGUI app can hold multiple exception handlers which you can register with app.on_exception. The default handler logs the traceback to the console.

With app.on_page_exception you independently define the UI of the displayed error page. We explicitly tried not to affect other exception handlers.

To avoid the default behavior of logging the traceback, you can clear the default handler like this:

app._exception_handlers.clear()

Note that this is an undocumented private API which could change anytime in the future.

[davetapley]

Understood, thanks for the fast reply.

I'll leave for now, but I welcome 👍🏻 from others who have a need for more handler management in the public API.