Broken DNS setup for mermaid.js.org

[ukleinek]

wanting to look at https://mermaid.js.org/ my browser tails to show that page with "Hmm. We’re having trouble finding that site.".
At a lower level the problem manifests itself as:

$ getent hosts mermaid.js.org
$ echo $?
2

where 2 means "One or more supplied key could not be found in the database.".

https://dnsviz.net/d/mermaid.js.org/dnssec/ shows several warnings. I think the relevant that makes resolution fail for me is

mermaid.js.org/CNAME: The server returned CNAME for mermaid.js.org, but records of other types exist at that name. See RFC 2181, Sec. 10.1.

Having a CNAME and other RRs at the same name is an invalid configuration that results in different breakages for different resolvers.
See RFC 2181, Sec. 10.1

Adding an entry to /etc/hosts helps to access the website.