cloneOutput helper function Map support

[Daennes]

Summary

The cloneOutput helper function currently uses JSON.stringify and JSON.parse to perform cloning. However, this approach does not support Map objects.
https://github.com/MeshJS/mesh/blob/main/packages/mesh-transaction/src/mesh-tx-builder/index.ts#L1799-L1801

As a result, when a Mesh Data object containing a Map is used as inline output data, the Map contents are lost during the cloning process.

Mesh Data Object can contain Maps
https://github.com/MeshJS/mesh/blob/main/packages/mesh-common/src/types/data.ts#L6

I encountered this issue when generating CIP68 metadata with metadataToCip68 and then using it in .txOutInlineDatumValue(cip68Metadatum, "Mesh") while creating a transaction.

Could be fixed with structuredClone

export const cloneOutput = (output: Output): Output => {
  return structuredClone(output);
};

Steps to reproduce the bug

No response

Actual Result

Empty Map and error in TX creation

Error:

Error: TypeError: Cannot convert undefined to a BigInt
    at BigInt (<anonymous>)
    at toPlutusData (.../node_modules/@meshsdk/core-cst/dist/index.js:4092:13)
    at .../node_modules/@meshsdk/core-cst/dist/index.js:4068:22
    at Array.forEach (<anonymous>)
    at toPlutusList (.../node_modules/@meshsdk/core-cst/dist/index.js:4067:11)
    at toPlutusData (.../node_modules/@meshsdk/core-cst/dist/index.js:4093:13)
    at fromBuilderToPlutusData (.../node_modules/@meshsdk/core-cst/dist/index.js:4167:12)
    at CardanoSDKSerializer.serializeOutput (.../node_modules/@meshsdk/core-cst/dist/index.js:6026:29)
    at getOutputMinLovelace (.../node_modules/@meshsdk/transaction/dist/index.js:5114:18)
    at _MeshTxBuilder.calculateMinLovelaceForOutput (.../node_modules/@meshsdk/transaction/dist/index.js:5028:12)

Expected Result

Non empty Map after clone and working TX

SDK version

1.9.0-beta.71

Environment type

• Node.js
• Browser
• Browser Extension
• Other

Environment details

No response

[HinsonSIDAN]

@twwu123 please help check if its bug

[OscarOzaine]

Confirmed — this is a reproducible bug (cc @HinsonSIDAN @twwu123).

Root cause is exactly as @Daennes described: cloneOutput uses a JSON round-trip, so a Map inside a Mesh Data inline datum (e.g. CIP-68 metadata from metadataToCip68) is cloned to an empty {}. Because cloneOutput runs inside getOutputMinLovelace, any build with a Map-bearing inline datum then fails in serializeOutput with Cannot convert undefined to a BigInt.

I opened #831 with the suggested structuredClone fix plus regression tests (Map + bigint preserved, deep-copy independence, plain output unaffected). structuredClone also matches how the builder already clones txOutput in tx-builder-core.ts.