jsdom@28's JSDOMDispatcher passes an onError handler incompatible with Node 22's bundled undici, causing InvalidArgumentError (UND_ERR_INVALID_ARG) on CI. Stubbing globalThis.fetch prevents the dispatcher from being invoked. The previous uncaughtException handler was insufficient — it caught the wrong error code and didn't handle unhandled rejections. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>