Specifically `An update to * inside a test was not wrapped in act(...)` is not logged when a prior update threw. 

<details>
<summary>failing test (#21766)</summary>

```js
// @gate __DEV__
it('warns if a setState is called outside of act(...) after a component threw', () => {
  let setValue = null;
  function App({defaultValue}) {
    if (defaultValue === undefined) {
      throw new Error();
    }
    const [value, _setValue] = React.useState(defaultValue);
    setValue = _setValue;
    return value;
  }

  expect(() => {
    act(() => {
      render(<App defaultValue={undefined} />, container);
    });
  }).toThrow();

  act(() => {
    rerender(<App defaultValue={0} />, container);
  });

  expect(() => setValue(1)).toErrorDev([
    'An update to App inside a test was not wrapped in act(...).',
  ]);
});
```
</details>

What I noticed is that in https://github.com/facebook/react/blob/27c9c95e23ddedb9163373950e364dd62038f6c0/packages/react-reconciler/src/ReactFiberWorkLoop.new.js#L2855-L2865
the `executionContext` will still equal `RetryAfterError` when we would expect a "missing act" warning.

"missing act" warnings are working as expected with legacy roots.
concurrentRoot.unmount();
        concurrentRoot = null;
      }
    };
    const rerenderConcurrent = el => {
      concurrentRoot.render(el);
    };
    runActTests(
      'concurrent mode',
      renderConcurrent,
      unmountConcurrent,
      rerenderConcurrent,
    );
  }
  
  let legacyDom = null;
  function renderLegacy(el, dom) {
    legacyDom = dom;
    ReactDOM.render(el, dom);
  }
  function unmountLegacy(dom) {
    legacyDom = null;
    ReactDOM.unmountComponentAtNode(dom);
  }
  function rerenderLegacy(el) {
    ReactDOM.render(el, legacyDom);
  }
  runActTests('legacy mode', renderLegacy, unmountLegacy, rerenderLegacy);
  describe('unacted effects', () => {
    function App() {