Fixing Vitest CI Worker Crashes by Switching from jsdom to happy-dom

Our Vitest suite passed every time locally, but GitHub Actions failed before executing a single test. Instead of failed assertions, every test worker crashed during startup, leaving us with 0% coverage and a broken CI pipeline.

After narrowing the issue down to our test environment, we replaced jsdom with happy-dom. That change resolved the worker crashes in our environment and restored a stable GitHub Actions pipeline.

Environment Context

To help determine if this applies to your setup, here is the stack where we encountered this:

Framework: Next.js (App Router)