Improve autobalancing errors when change has no lovelace

[carbolymer]

Changelog

- description: |
    Improve autobalancing errors when change has no lovelace
    `checkMinUTxOValue` has its arguments flipped.
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
   - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
   - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

Previously for txout with 0 lovelace and some non-ada assets the returned error was about negative balance, which doesn't make sense.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[Copilot]

Copilot wasn't able to review any files in this pull request.

Files not reviewed (2)

• cardano-api/src/Cardano/Api/Internal/Fees.hs: Language not supported
• cardano-api/test/cardano-api-test/Test/Cardano/Api/Orphans.hs: Language not supported

[Jimbo4350]

Nice 👍

[Jimbo4350]

You may want to give @mkoura a heads up if he is depending on the error output for this failure case.

[palas]

I have limited understanding of this code. But I am pretty confident it is all refactoring except for the addition of the TxBodyErrorAdaBalanceTooSmall error, which I don't understand why it is there, but I imagine it is correct.

I just added a suggestion that I think can improve readability a little bit

[palas]

I would put this check outside the if, even though I understand it is equivalent (since the balanceCheck already has an exception for this). But the code would be slightly simpler

[carbolymer]

Good idea. I think I'll do a single check for the txout emptiness in the balance check only i.e. I'll change the output type to:

balanceCheck :: ... -> Either (TxBodyErrorAutoBalance era) IsEmpty

data IsEmpty = Empty | NonEmpty