500 Internal Server Error when send request to https://cht.sh/:shell-x/

When I send request to https://cht.sh/:shell-x/, I receive internal server :

$ curl https://cht.sh/:shell-x/ -v
< HTTP/1.1 500 INTERNAL SERVER ERROR
< Server: nginx/1.13.12
< Date: Tue, 18 Apr 2023 09:53:32 GMT
< Content-Type: text/html; charset=utf-8
< Content-Length: 290
< Connection: keep-alive

Start by reproducing the failure with `curl https://cht.sh/:shell-x/ -v` and inspect the request path for the `shell-x` cheatsheet endpoint. The issue provides no source file or test location; done means the endpoint no longer returns HTTP 500 and the response can be verified with the same command.

Written by the indexing model from the issue text.