feat(toJSON): add optional iterator parameter for plain JSON output

[Refzlund]

Summary

This PR enhances the toJSON() method with an optional iterator parameter that controls whether Symbol.iterator is included in the serialized output.

Changes

src/result.ts

• Enhanced toJSON() signature: Added optional generic parameter TIterator extends boolean = true to control iterator inclusion
• New Result.PlainJSON type: A clean JSON type without Symbol.iterator or Result.symbol, useful for serialization to external systems
• Conditional return type: toJSON(false) returns Result.PlainJSON, toJSON() or toJSON(true) returns Result.JSON (with iterator)
• Refactored Result.JSON type: Now extends PlainJSON to avoid code duplication

tests/serialization.test.ts

• Added comprehensive tests for the new iterator parameter
• Tests cover both Ok and Err results with toJSON(false)
• Type tests verify correct type inference for Result.JSON vs Result.PlainJSON
• Tests verify Symbol.iterator presence/absence based on parameter

Use Case

When serializing Results for transport (e.g., HTTP responses, message queues), you often want plain JSON without symbols:

// Before: Had to manually strip symbols or work around it
const response = result.toJSON()
delete response[Symbol.iterator]

// After: Clean and type-safe
const response = result.toJSON(false)
// => { ok: true, value: ... } or { ok: false, code: ..., message: ... }

Breaking Changes

None. The default behavior (toJSON()) remains unchanged and returns Result.JSON with the iterator included.

[changeset-bot]

🦋 Changeset detected

Latest commit: c16b748

The changes in this PR will be included in the next version bump.

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