I hate this so much because you can’t nicely serialise a BigInt as JSON. Using a string is nicer but it
only makes sense where int64 is used as an ID, not where it’s used as a number; and you don’t wanna have to configure this per field per query.
IMO, I'm tending toward thinking that having types on your readable serialization format is a mistake, and that they should be always input to the (de)serializer instead.
In JS - BigInt is 64bit integer.
In anything else - BigInt is a arbitrarily large integer.