`weakrefobject.c` doesn't handle `allocate_weakref` failures

[colesbury]

Bug report

We need to handle the case where allocate_weakref returns NULL due to an out-of-memory error.

cpython/Objects/weakrefobject.c

Lines 428 to 439 in dc03ce7

	PyWeakReference *newref = allocate_weakref(type, obj, callback);
	insert_weakref(newref, list);
	UNLOCK_WEAKREFS(obj);
	return newref;
	}
	else {
	// We may not be able to safely allocate inside the lock
	PyWeakReference *newref = allocate_weakref(type, obj, callback);
	LOCK_WEAKREFS(obj);
	insert_weakref(newref, list);
	UNLOCK_WEAKREFS(obj);
	return newref;

Linked PRs

• gh-121652: Handle allocate_weakref returning NULL #121653
• [3.13] gh-121652: Handle allocate_weakref returning NULL (GH-121653) #121721