[emmanuel-musau]

toString threw Do not know how to serialize a BigInt on any InlineDatum, UTxO, TxOut, TransactionOutput or Redeemer whose data held an integer or a constructor. Their toJSON returned the data as it is, and Inspectable.format is a plain JSON.stringify. Data without integers rendered wrongly: the byte string ab as {"0": 171} and the map {1: 2} as {}.

The new Data.toJSON returns data in the encoded form DataSchema already writes: an integer as a decimal string, a byte string as hex, a map as [key, value] pairs and a constructor as { index, fields }. InlineDatum, Redeemer, RedeemerMap and TransactionWitnessSet use it, which also fixes TxOut, UTxO and BabbageTransactionOutput through the datum. RedeemerValue, which RedeemerMap.get returns, had no toJSON and gains one.

BabbageTransactionOutput.toString threw on every output, datum or not, because Value.toJSON returned coin as a bigint. It now writes coin as a decimal string, as MultiAsset already writes quantities.

console.log and util.inspect still show the data itself, with bigint integers and Uint8Array bytes. The changeset is a minor, since toJSON().data and toJSON().coin change type.

In this form an integer and a byte string can render the same, Data.int(12n) and the bytes 12 both as "12", and an empty map and an empty list both as []. It only affects display; CBOR, hashes and transaction ids do not go through toJSON.

Closes #685