CONSOLE WARNING: line 20: Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check https://xhr.spec.whatwg.org/.
CONSOLE ERROR: line 24: Failed to load http://nonexistent-origin.web-platform.test:8001/: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://web-platform.test:8001' is therefore not allowed access. The response had HTTP status code 404.
