I have the same with JSON. Sure, when I'm using JSON/REST APIs everything works fine, but I deal a lot with JSON on disk, and it happens a lot that you have sloppy JSON because people hand-edit it. Trailing commas and comments are the most common, but sometimes you just have js/python object literals dumped into a file.

In every language I work in, I find myself writing a lenient JSON parser. So far, Python, C++, and Nim (for JS, there is already JSON5).

I am also working on a whitespace and comment preserving parser that round-trips, so you can change a value in a configuration file without loosing comments. (Currently, I always produce standard JSON so compatibility is not an issue.)

I have been thinking about publishing these parsers, but after seeing how much abuse and nasty comments the JSON5 guy got, I have been holding off...