User's browser showed 404 and CORS errors for Carto tiles
even though curl shows the URLs return 200 with CORS headers.
Most likely the browser had cached earlier failed attempts.
Added a per-tile cache-buster (?v=Date.now()+random) to the
fetch URL so every tile request bypasses the browser's HTTP
cache. Removed the diagnostic console.log lines since the
issue is identified (browser cache).
Richard Zink
83fd829cd5