errore

# errore Go-style error handling for TypeScript. Functions return errors instead of throwing them — but instead of Go's two-value tuple (`val, err`), you return a single `Error | T` union. Instead of checking `err != nil`, you check `instanceof Error`. TypeScript narrows the type automatically. No wrapper types, no Result monads, just unions and `instanceof`. ```ts const user = await getUser(id) if (user instanceof Error) return user // early return, like Go console.log(user.name) // TypeScript knows: User ``` ## Rules 1. Always `import * as errore from 'errore'` — namespace import, never destructure 2. Never throw for expected failures — return errors as values 3. Never return `unknown | Error` — the union collapses to `unknown`, breaks narrowing. Common trap: `res.json()` returns `unknown`, so `return await res.json()` makes the return type `MyError | unknown` → `unknown`. Fix: cast with `as` → `return (await res.json()) as User` 4. Avoid `try-catch` for control flow — use `.catch()` for async boundaries, `errore.try` for sync boundaries 5. Use `createTaggedError` for domain errors — gives you `_tag`, typed properties, `$variable` interpolation, `cause`, `findCause`, `toJSON`, and fingerprinting 6. Let TypeScript infer return types — only add explicit annotations when they improve readability (complex unions, public APIs) or when inference produces a wider type than intended 7. Use `cause` to wrap errors — `new MyError({ ..., cause: originalError })` 8. Use `| null` for...