In this [issue](https://github.com/facebook/react/issues/23373), when you navigate to [this app](https://next-rsc-notes.vercel.app/note/1646289027680) and inspect the sidebar in the components tab, you will get this error:

![image](https://user-images.githubusercontent.com/2735514/158241727-64eba8f9-5ac2-4aa7-bffa-ff9b3174a261.png)

 This is a user error. One of the components in the user's app thrown. However, the UI for this is confusing, because it seems like it's a DevTools error. We've gotten a lot of bug reports like this, and it would be good to differentiate between DevTools bugs and bugs in the app. For this task:

- [ ] Build the React DevTools extension locally (instructions [here](https://github.com/facebook/react/tree/main/packages/react-devtools-extensions)) and reproduce the error
- [ ] Figure out a way to have the front end be able to differentiate whether the error is a error within DevTools or within the user's app
- [ ] Design/implement a better UI to help app developers distinguish between these two cases
and give React time to process the Fast Refresh delay.
    untrackFibersSet.add(fiber);
     React may detach alternate pointers during unmount;
     Since our untracking code is async, we should explicily track the pending alternate here as well.
    const alternate = fiber.alternate;
    if (alternate !== null) {
      untrackFibersSet.add(alternate);
    }
    if (untrackFibersTimeoutID === null) {
      untrackFibersTimeoutID = setTimeout(untrackFibers, 1000);
    }
  }
  const untrackFibersSet: Set<Fiber> = new Set();
  let untrackFibersTimeoutID: TimeoutID | null = null;
  function untrackFibers() {
    if (untrackFibersTimeoutID !== null) {
      clearTimeout(untrackFibersTimeoutID);
      untrackFibersTimeoutID = null;
    }
    untrackFibersSet.forEach(fiber => {
      const fiberID = getFiberIDUnsafe(fiber);
      if (fiberID !== null) {
        idToArbitraryFiberMap.delete(fiberID);
         A
        clearErrorsForFiberID(fiberID);
        clearWarningsForFiberID(fiberID);
      }
      fiberToIDMap.delete(fiber);
      const {alternate} = fiber;
      if (alternate !== null) {