fantasia-neverthrow

name: fantasia-neverthrow description: >- Use the neverthrow Result / ResultAsync pattern instead of try/catch for recoverable failures. Apply when touching error paths, IPC wrappers, parsers, or refactors around thrown errors.

Neverthrow error handling

When to follow

• Anticipated failures: IPC, parse edge cases, cancellation, clipboard, optional APIs
• Refactoring legacy try/catch or swallowed .catch

See neverthrow.mdc.

Core API (Neverthrow v8)

• ok(value), err(error)
• Result.fromThrowable(fn, mapError)
• ResultAsync.fromPromise(promise, mapError); fromSafePromise when rejection unexpected
• match, unwrapOr, map, mapErr, andThen, orElse
• safeTry: generator yield* result for sequential steps

Prefer finally on Promise chains for cleanup-only side effects.

Preload exclusion

src-electron/contentBridgeAPIs/** — sandboxed preload bundle. No neverthrow import. Use Promise.then/.catch, URL.canParse, early returns. src-electron/shared/** reachable from preload: same rule. Renderer, main, helpers/ still prefer Result / ResultAsync.

Links

• neverthrow documentation