Type Alias CommandResult<V>

CommandResult:
| { ok: true; value?: V; error?: undefined }
| { ok: false; error: Error; value?: undefined }

Result of a dispatch/query — a discriminated union on ok.

if (result.ok) narrows away error; on the failure arm error is a guaranteed Error (no ! or ?. needed). value stays optional on the success arm because void commands legitimately produce no value.