See https://github.com/w3c/web-platform-tests/pull/5123 for a test.
I can get to the source code of the test via the above link (after some digging around), but I can't figure out how to run it from there. Would it be feasible to provide a link or attachment that demonstrates the issue with a single click?
I think: https://w3c-test.org/submissions/5123/XMLHttpRequest/send-entity-body-document-bogus.htm
Yeah, until it lands that would be the location to check (or apply the patch to your local web-platform-tests).
Safari Technical Preview 150 passes all these test: https://wpt.fyi/results/xhr/send-entity-body-document-bogus.htm?label=master&label=experimental&aligned&view=subtest&q=send%20entity%20bogus Is else needed here? Thanks!
Seems like config changed. Nice!