Warning/hint on redundant `except ...`

[arnetheduck]

Summary

Introduce a warning for dead exception handlers

Description

In the following code snippet, no exceptions can be raised and therefore, the exception handler is dead code which can be removed. Similar to other cases of dead code, this should have a warning:

proc f() {.raises: [].} = discard

try:
  f()
except CatchableError: # No exceptions can result from `f`
  discard

Alternatives

No response

Examples

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Backwards Compatibility

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Links

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[arnetheduck]

This could be a warning or a hint - it should probably follow the same defaults as other dead-code detectors such as "variable not used" and "private proc not used"