Improve ValidationIssue enum

[ajevans99]

Description

This pull request introduces two major updates: the addition of a CustomStringConvertible implementation for the JSONValue type and a significant refactor of the ValidationIssue error cases to include more detailed context in validation errors. These changes improve the clarity and debugging capabilities of the JSON schema validation library.

Enhancements to JSONValue:

• Added a CustomStringConvertible implementation to the JSONValue type, allowing for a human-readable string representation of JSON values. This includes formatted output for strings, numbers, objects, arrays, booleans, and null values. (Sources/JSONSchema/JSONValue/JSONValue.swift)

Refactor of ValidationIssue:

• Refactored the ValidationIssue enum to include detailed contextual information for all validation errors. For example:
  • typeMismatch now specifies the expected and actual types.
  • notEnumCase includes the value being validated and the allowed values.
  • Array-related errors like containsInsufficientMatches and containsExcessiveMatches now include counts and thresholds.
  • Object-related errors like exceedsMaxProperties and belowMinProperties now include property counts and limits.
  • Logical and conditional errors (e.g., oneOfFailed, conditionalFailed) now include associated validation errors for better debugging. (Sources/JSONSchema/Validation/Errors/ValidationIssue.swift)

Updates to Validation Logic:

• Updated all validation methods in Keywords+Assertion.swift and Keywords+Applicator.swift to throw the newly refactored ValidationIssue cases with detailed context. This ensures that all validation errors provide specific information about what failed and why. [1] [2] [3] [4] [5] and others)

Closes #39

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Additional Notes

Add any other context or screenshots about the pull request here.

[Copilot]

Pull Request Overview

This PR refactors the JSON schema validation error reporting by introducing detailed context for each error case and adds a human‐readable string representation for JSON values. Key changes include:

• Updating all ValidationIssue error cases to include detailed associated values.
• Adjusting validation methods across assertion and applicator keywords to throw enriched errors.
• Adding a CustomStringConvertible implementation for JSONValue.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
Tests/JSONSchemaTests/KeywordTests.swift	Updated tests to reflect new, more descriptive error cases.
Sources/JSONSchema/Validation/Errors/ValidationIssue.swift	Refactored ValidationIssue enum to include associated values and improved descriptions.
Sources/JSONSchema/Keywords/Keywords+Assertion.swift	Adjusted error throwing to use the new error cases with detailed context.
Sources/JSONSchema/Keywords/Keywords+Applicator.swift	Updated error throwing in applicator methods with detailed error information.
Sources/JSONSchema/JSONValue/JSONValue.swift	Added CustomStringConvertible conformance for more readable string representations.