Bug report

Bug description:

There is a theoretical crash path in the new zstd module that can be avoided with Py_XSETREF. PR incoming.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-134885: zstd: Use Py_XSETREF #134886
• [3.14] gh-134885: zstd: Use Py_XSETREF (GH-134886) #134922