Extremely long numbers should be truncated at read time rather than trying to convert very large strings.

[FFMG]

Very large number that we know cannot be handled, should be truncated as we read the value into string.

for example

{
  "" : 0.123456789123456789123456789
}

should limit 'a' to a=0.1234567891234567891 (or whatever the max len is).

in the case of int,

{
  "a" : 123456789123456789123456789
}

should convert to a=1.2345678912345678912e+27, (or something similar)

We should not read extremely large numbers in memory as it could cause memory issues and/or performance issues.

[FFMG]

If you look at rfc8259 there are no restrictions

So

{
  "a" : 123456789123456789123456789
}

would become

auto a = 1.2345678912345679e+26;

Maybe we should raise a warning that there was a loss of precision somewhere along the line, but that would still mean reading the full string so we know the final precision.