By giving the table to this function you make a promise to not modify the table while the json string is being created!
This is because we don't copy the table, we instead copy the pointer into a new Lua state where we then iterate/access it from another state/thread and if you modify it in any way you will experience a crash.
You still can access the table in that time, you are just not allowed to modify it.
It was observed that you can kinda modify the table though if you add new elements/the size of the table changes while its still creating the json string you will crash.