message: add explicit return type on ReleaseMap#addIfOpen
diff: @@ -147,7 +147,7 @@ export class ReleaseMap {
  )
  }
  - addIfOpen(finalizer: Finalizer) {
  + addIfOpen(finalizer: Finalizer): T.Async<O.Option<number>> {
  return pipe(
  this.ref,
  R.modify<T.Async<O.Option<number>>, State>((s) => {
  