Bulk Redirects Example script not working

Hi,

I am testing the example bulk redirect script hosted on developer . cloudflare . com

I am testing the script against worker.dev domain provided by the worker. I have made simple update to the const external domain and left a single line in the map.

Test redirect URL is “/testredirect1”. But browsing to https://my-worker.gav2665.workers.dev/testredirect1 returns Error 522.

Help a newbie out!
Appreciate it