Describe the bug

obj[key] = value and del obj[key] on a type that has sequence slots but no sq_ass_item (tuple, str, bytes, range, frozenset, a plain class) raise TypeError without calling key.__index__(). CPython converts the key first, so an exception from __index__, or IndexError for an oversized int, is raised instead of the TypeError.

Operating system

macOS

CPU architecture

ARM64

GraalPy version

master a3009f9 (Python 3.13.14); also reproduced on 25.0.2 (Python 3.12.8) and 25.4.4.1.1 (Python 3.13.14)

JDK version

No response

Context configuration

No response

Steps to reproduce

import operator

class RaisingIndex:
    def __index__(self):
        raise ZeroDivisionError

for f, args in [(operator.setitem, ((), RaisingIndex(), 0)),
                (operator.delitem, ('', RaisingIndex())),
                (operator.setitem, ('', 2**100, 0))]:
    try:
        f(*args)
    except Exception as e:
        print(type(e).__name__, e)

GraalPy master a3009f9:

TypeError 'tuple(EmptySequenceStorage[])' object does not support item assignment
TypeError '' object does not support item deletion
TypeError '' object does not support item assignment

Expected behavior

CPython 3.13.14 (same on 3.12.13):

ZeroDivisionError 
ZeroDivisionError 
IndexError cannot fit 'int' into an index-sized integer

Stack trace

Additional context

The statements t[RaisingIndex()] = 0 and del s[RaisingIndex()] take the same path. Types without sequence slots (int, object, types.GenericAlias) and non-index keys raise TypeError on both.

Root Cause

PyObjectSetItemGeneric converts the key with __index__ only in the specializations guarded by slots.sq_ass_item() != null; any other type falls into the @Fallback that raises TypeError (PyObjectSetItem.java#L125-L139), and PyObjectDelItemGeneric does the same (PyObjectDelItem.java#L118-L132). CPython's PyObject_SetItem and PyObject_DelItem convert an index key whenever the type has tp_as_sequence, before PySequence_SetItem / PySequence_DelItem look for sq_ass_item (abstract.c#L237-L252, #L271-L286).

Fix Suggestion

Add a specialization for mp_ass_subscript == null, sq_ass_item == null and slots.has_as_sequence() to both nodes that runs PyNumberAsSizeNode.executeExact(..., IndexError) on an index key before raising the existing TypeError.