Expose additional information about `ParseError`s

[khieta]

Category

Error message improvements

Describe the feature you'd like to request

#970 exposes ParseError in the public API as a struct with a private field. This means that users can do nothing with the resulting error beyond what is exposed through it's miette::Diagnostic implementation. So: they can print it out, see source location info, etc., but not match on the type of error (outside of matching on the error message text -- which we do not recommend!). We should expose the ParseError as an enum in accordance with #745. See EvaluationError and ValidationError for examples.

However, before we expose this error type there is some cleanup that needs to be done:

1. Flatten the ParseError structure to remove the distinction between ToCST and ToAST errors. This distinction shouldn't matter from a user's perspective.
2. Get rid of the Kind pattern since we've moved away from using this elsewhere in the code base (see Align EvaluationError and ExtensionFunctionLookupError with cedar#745 #860 and Flatten structs for validation errors and warnings #911).

Describe alternatives you've considered

No reponse

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change