Fix validation script after adding structured errors

[amanusk]

This does requires messages to be a list, which might not be what we want

[kkovaacs]

This is great -- but I don't think we should change the specification in that way just to make validation possible.

Looks like there's an open issue on @json-schema-tools/dereferencer for handling recursive schemas: json-schema-tools/dereferencer#608

Would it be possible to:

• rebase this branch to the current state of things (after merging the starknet_getStorageProof change)
• include just the schema fixes that are purely fixes and maybe skip that single change that makes the child CONTRACT_EXECUTION_ERROR an array?

[amanusk]

Agree that it is a bit backwards and not ideal.
I'll try exploring ways to fix the validation script in a way that does not require this change.
But it would be a shame to forgo all validations going forward, and since this component is in the main API schema, it breaks validating all other schemas as well :(