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.
unstable_strictMode: true,
        });
        root.render(<App />);
        Scheduler.unstable_flushAll();
      }).toErrorDev([
        'An update to App ran an effect, but was not wrapped in act(...)',
      ]);
    });
  });
});
function runActTests(label, render, unmount, rerender) {
  describe(label, () => {
    beforeEach(() => {
      jest.resetModules();
      React = require('react');
      ReactDOM = require('react-dom');
      ReactTestUtils = require('react-dom/test-utils');
      Scheduler = require('scheduler');
      act = ReactTestUtils.act;
      container = document.createElement('div');
      document.body.appendChild(container);
    });
    afterEach(() => {
      unmount(container);
      document.body.removeChild(container);
    });
    describe('sync', () => {
      
      it('can use act to flush effects', () => {
        function App() {