This is very valuable! Thank you!
Perhaps that's the secret to lua's success: they got the basics so wrong that they can't fall into the trap of chasing the dream of becoming a better language, focusing on becoming a better implementation instead. Or perhaps even more important: not changing at all when it's obviously good enough for the niche it dominates.
One can read through “mystdlib” part of any meaningful Lua-based project to see it. Things you’ll likely find there are: NIL, poor man’s classes, __newindex proxying wrapper, strict(), empty dict literal for json, “fixed” iteration protocols.
You don’t even have to walk too far, it’s all right there in neovim: https://neovim.io/doc/user/lua.html