What should I return is right case when the type is void, Either<Error, void>

[MiniSuperDev]

import * as E from 'fp-ts/lib/Either';

function fun(): E.Either<Error, void> {
  return E.right(void); // Expresion expected.
}

Or should I use other type instead of void?

thank you

[0x706b]

void is a keyword that discards the value of the expression that follows it. undefined or void 0 would work. However, Option<Error> might be a more simple way to model this type