config.discard_classes not support lambda

[hxx]

Description

since config.ignore_classes support lambda, but config.discard_classes not, I need this feature to maintain the same behavior as before when config.ignore_classes deprecated

Describe the solution you'd like

add lambda support for config.discard_classes

Describe alternatives you've considered

Additional context

[luke-belton]

Hi @hxx 👋

The discard_classes config option was introduced by #597 - it was designed to conveniently discard classes by name or regex match.

If you need to use a callback to identify particular classes for discard, you could take a look at the add_on_error callback. Returning false from this callback would discard the event.