del state.missing raises KeyError instead of AttributeError

[sungbin1015]

State.__getattr__ converts the KeyError from the underlying dict into an AttributeError, but State.__delattr__ does not, so deleting an attribute that is not set leaks a bare KeyError:

from starlette.datastructures import State

state = State()

try:
    state.missing
except Exception as exc:
    print("getattr ->", type(exc).__name__, exc)

try:
    del state.missing
except Exception as exc:
    print("delattr ->", type(exc).__name__, exc)

Output on main (ff5b4df and later, Python 3.11):

getattr -> AttributeError 'State' object has no attribute 'missing'
delattr -> KeyError 'missing'

Expected: del state.missing / delattr(state, "missing") raise AttributeError, like getattr does and like any regular object. Code that guards an optional cleanup with except AttributeError or contextlib.suppress(AttributeError) around del request.state.x does not catch the current exception.

The cause is in starlette/datastructures.py:

def __getattr__(self, key: Any) -> Any:
    try:
        return self._state[key]
    except KeyError:
        message = "'{}' object has no attribute '{}'"
        raise AttributeError(message.format(self.__class__.__name__, key))

def __delattr__(self, key: Any) -> None:
    del self._state[key]

__delitem__ raising KeyError is correct for the mapping-style access; only the attribute-style __delattr__ looks inconsistent. A fix would be the same try/except KeyError as in __getattr__. I'm not opening a PR for it; if you agree it is a bug it is a two-line change either way.

Related work. I searched discussions, issues and PRs (open and closed) for State __delattr__, delattr KeyError state and request.state del attribute KeyError. The closest are #2995 (asks whether an attribute can be removed from app.state; the answer shows del app.state.stuff for an existing attribute) and #2389 (asks for a state.get). Neither mentions the exception type for a missing attribute, and none of the open PRs that touch starlette/datastructures.py changes State.

Found with AI assistance (Claude Code) and reproduced locally with the snippet above.

[kgeminicdev]

Reproduced on current main (0a15da3). __getattr__ translates the KeyError, __delattr__ just does del self._state[key], so the dict's KeyError leaks through:

starlette/starlette/datastructures.py

Lines 689 to 697 in 0a15da3

	def __getattr__(self, key: Any) -> Any:
	try:
	return self._state[key]
	except KeyError:
	message = "'{}' object has no attribute '{}'"
	raise AttributeError(message.format(self.__class__.__name__, key))
	def __delattr__(self, key: Any) -> None:
	del self._state[key]

Until it's changed, either of these works on current releases:

if "x" in request.state:
    del request.state.x

with contextlib.suppress(AttributeError, KeyError):
    del request.state.x

in works because State defines __iter__. I'd include KeyError in the suppress so the code keeps working after a fix lands.