Your code appears to have a bug where if the arrow keys trigger a change of direction twice in a single frame interval, it can mistakenly send the snake back on itself.

What an honor. I got a high score of seven.

$ curl -I https://drop-e7e6d363-601.important-seat.workers.dev/ curl: (7) Failed to connect to drop-e7e6d363-601.important-seat.workers.dev port 443 after 47 ms: Couldn't connect to server

Tried from two hosts, different countries.