Use MonadError for 'LedgerState'. Add Show LedgerState, IOException handling in foldBlocks

[carbolymer]

Changelog

- description: |
    Use MonadError for 'LedgerState'. Add `Show LedgerState`, `IOException` handling in `foldBlocks`
# 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
   - improvement    # QoL changes e.g. refactoring
  # - 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

MonadError e m allows to use functions without extra lifting if we need to use them in monad stacks with ExceptT underneath.

How to trust this PR

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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

[smelc]

Nice API enhancement 👍

[smelc]

Nice change ❤️

I'm not a big fan of those ExceptT return types. Constrained monads like you did is better IMHO.

[smelc]

Don't we want to put this constraint in the other package defined in this (line 319)? Being consistent could avoid surprises later on.

[carbolymer]

Yeah, this constraint is wrong - breaks build with older ghc which require mtl-2.2.2. I've just pushed a compatiblity shim in Cardano.Api.Utils.