Bug report

Bug description:

This branch is currently not covered by the tests:

We should add a test case for it. I can send a PR shortly ;)

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-121982: csv module: Test invalid quoting constant #121983
• [3.12] gh-121982: csv: Add a test case for invalid quoting constant. (GH-121983) #124925
• [3.13] gh-121982: csv: Add a test case for invalid quoting constant. (GH-121983) #124926