fix(dispatcher): explicitly disable exception chaining

[lengau]

In these cases, the chaining doesn't provide useful additional data.

Drive-by: updates ruff to 0.2

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[mr-cal]

LGTM (I didn't test but I am assuming the traceback will look the same)

[lengau]

@mr-cal This does change the traceback, since it sets the __context__ to None rather than the previous exception. However, the context exceptions aren't useful to either an end user or a developer using this library since they're implementation details (they're mostly KeyError in places where we use dictionaries and in one case a StopIteration where we call next()). In all cases, these are raising ArgumentParsingError, which the application should always catch and display (but should never care about context).

[mr-cal]

@mr-cal This does change the traceback, since it sets the __context__ to None rather than the previous exception. However, the context exceptions aren't useful to either an end user or a developer using this library since they're implementation details (they're mostly KeyError in places where we use dictionaries and in one case a StopIteration where we call next()). In all cases, these are raising ArgumentParsingError, which the application should always catch and display (but should never care about context).

That sounds reasonable to me, thanks for the explanation!