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.
}
export function popRenderLanes(fiber: Fiber) {
  subtreeRenderLanes = subtreeRenderLanesCursor.current;
  popFromStack(subtreeRenderLanesCursor, fiber);
}
function prepareFreshStack(root: FiberRoot, lanes: Lanes) {
  root.finishedWork = null;
  root.finishedLanes = NoLanes;
  const timeoutHandle = root.timeoutHandle;
  if (timeoutHandle !== noTimeout) {
     
     
    root.timeoutHandle = noTimeout;
     
    cancelTimeout(timeoutHandle);
  }
  if (workInProgress !== null) {
    let interruptedWork = workInProgress.return;
    while (interruptedWork !== null) {
      unwindInterruptedWork(interruptedWork, workInProgressRootRenderLanes);
      interruptedWork = interruptedWork.return;
    }
  }
  workInProgressRoot = root;
  workInProgress = createWorkInProgress(root.current, null);
  workInProgressRootRenderLanes = subtreeRenderLanes = workInProgressRootIncludedLanes = lanes;
  workInProgressRootExitStatus = RootIncomplete;
  workInProgressRootFatalError = null;
  workInProgressRootSkippedLanes = NoLanes;
  workInProgressRootUpdatedLanes = NoLanes;