[bug]: empty result of lazy component doubles next node

[aleksandrjet]

I added test, which shows that empty result of Lazy component doubles next node while hydration.

<main>
  <Suspense fallback={<p>will be never showed while hydration</p>}>
    <Lazy /> <!-- if it returns null, the next dom node will be doubled -->
  </Suspense>
  <p>will be rendered twice after hydration</p>
</main>

This seems, it happens because error, when rendering a lazy component:

// compat/src/suspense.js:261
if (!component) {
  throw prom;
}

Maybe we incorrect handle this error. I don't understand, why we need to remove last node from excessDomChildren and assing a value of oldDom to newVNode._dom

// src/diff/index.js:260
catch (e) {
  newVNode._original = null;
  if (isHydrating || excessDomChildren != null) {
    newVNode._hydrating = !!isHydrating;
    
    // We think, that oldDom will be replaced
    // a new node, which will be returned by Lazy. 
    // But this may be not so, because Lazy can return null
    newVNode._dom = oldDom;
    excessDomChildren[excessDomChildren.indexOf(oldDom)] = null;
  }
}

I tried to add additional handling for this error, but it breaks some of tests for suspense-hydration, despite the fact current test begun work

// src/diff/index.js:260
catch (e) {
  newVNode._original = null;
  if (isHydrating || excessDomChildren != null) {
    newVNode._hydrating = !!isHydrating;
    
    if (newVNode.type.displayName !== 'Lazy') {  // it breaks other tests
      newVNode._dom = oldDom;
      excessDomChildren[excessDomChildren.indexOf(oldDom)] = null;
    }
  }
}

I am looking for a solution and i need help of community. Now i think it can not fix by additional error handling, because at moment of processing node when hydration we don't know, what will return Lazy

P.S. I understand, that lazy component with empty result is not the best idea. But it give unpredictable result with doubles nodes. I think, it should working or throw error