avoid calling peekMeta when meta does not exist

[bekzod]

differentiate between not passing meta and meta not existing.

many meta related functions allow passing meta as last argument and do check if meta passed as following:

let meta = _meta === undefined ? peekMeta(obj) : _meta;

is such case peekMeta() is called even if last argument is passed as undefined since meta does not exist, to avoid it made peekMeta to return null instead of undefined

[bekzod]

closing this for now, it is typescript lint nightmare