@Test public void emptyPlan_errorPropagation() {

  ExceptionPlan<String> plan = new ExceptionPlan<>();
  MyError error = new MyError();
  Maybe<ExceptionPlan.Execution<String>, MyError> maybe = plan.execute(error);
  assertSame(error, assertThrows(MyError.class, () -> maybe.orElseThrow(e -> e)));
}