ignore `undefined` in stringifying

[adhami3310]

JSON.stringify is to ignore those.

error: "null" and "undefined" values are not supported

[DecimalTurn]

The decision to throw an error when undefined values are present was made before I forked the project. I can see why it would be more intuitive to just ignore them since that's what JSON.stringify does.

Looking at what smol-toml does, it also ignores undefined values as long as they are not inside of an array. This makes sense since JSON.stringify would replace them with null and it's still not supported in TOML v1.1 (this might change in v1.2).

For this project, I'd be OK with the ignoring of undefined values except when inside an array, but behavior for null would remain the same. @adhami3310, would that solve your use case?

NB.: . Once, TOML supports null, we might change the behavior to return null when an element is undefined inside an array, but that's for another day.

[adhami3310]

yea i'm mostly affected by it when it's the value to a key (in a table). it just happens to be hard to remove undefineds in that context. As { b : undefined } carry the same thing as {} when doing .b.