fix bug json about json

[trentm]

Working with integers greater than 2**53 -1 is fraught. JS has a Number.MAX_SAFE_INTEGER above which precision is lost.

> 1234567890123456789012 > Number.MAX_SAFE_INTEGER
true

At or above 1e21, JS represents numbers with scientific notation:

> 1e20
100000000000000000000
> 1e21
1e+21

If you need to keep precision for integers above MAX_SAFE_INTEGER, you should use BigInt if you can. Unfortunately, BigInt doesn't serialize to JSON:

> obj = {"id":1234567890123456789012n,"name":"edwin"}
{ id: 1234567890123456789012n, name: 'edwin' }
> JSON.stringify(obj)
Thrown:
TypeError: Do not know how to serialize a BigInt
    at JSON.stringify (<anonymous>)

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt#Use_within_JSON