Description:
------------
See https://nigeltao.github.io/blog/2021/json-with-commas-comments.html for more information.

It is quite common to have trailing commas in JSON, and a lot of parsers support it. I believe this could be trivially supported by PHP, even if you skip adding support for comments.

Test script:
---------------
json_decode( '{"a":1,}', JSON_THROW_ON_ERROR );