initconfig.c: `SET_ITEM` macro leaks dict on expression failure

[Wulian233]

Bug report

Bug description:

Parent: #146102

SET_ITEM macro at line 510-521: when the expression (e.g., PyLong_FromLong) returns NULL, return NULL at line 514 leaks the dict allocated at line 505. The PyDict_SetItemString failure path correctly uses goto fail.

CPython versions tested on:

CPython main branch

Linked PRs

• gh-146244: Fix initconfig.c SET_ITEM macro leaks dict on expression failure #146246

[Wulian233]

I’m currently unable to add the parent issue #146102 . I would appreciate it if someone could help add it:)