A reader created in the flush that clears an upstream error shows an empty hole instead of the async memo's result #4378

const [s, setS] = createSignal(3);
const m0 = createMemo(() => {
  const v = 1 + latest(s);
  if (v % 4 === 0) throw new Error("m0"); // throws at s = 3
  return v;
});
const m1 = createMemo(() => fetchM1(1 + m0())); // at s = 2 asks for 4, which rejects
const [epoch, setEpoch] = createSignal(1);

render(() => (
  <Errored fallback={e => "[ERR]"}>
    <Loading fallback="[LOAD]">
      <Show when={epoch()} keyed>
        <span>{m1()}</span>
      </Show>
    </Loading>
  </Errored>
), el);
// [ERR]
setS(2);
setEpoch(2); // same batch: the <span> reader is recreated in the flush that applies the write
// settle every request