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### Which website or app were you using when the bug happened?

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### What were you doing on the website or app when the bug happened?

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1. <!-- FILL THIS IN -->
2. <!-- FILL THIS IN -->
3. <!-- FILL THIS IN -->

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### Generated information

DevTools version: 4.13.1-93782cfed2

Call stack:
    at chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:21447:43
    at bridge_Bridge.emit (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:19607:22)
    at chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:19767:12
    at listener (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:37788:39)

Component stack:
(none)

GitHub URL search query:
https://api.github.com/search/issues?q=Cannot%20add%20child%20%20to%20parent%20%20because%20parent%20node%20was%20not%20found%20in%20the%20Store.%20in%3Atitle%20is%3Aissue%20is%3Aopen%20is%3Apublic%20label%3A%22Component%3A%20Developer%20Tools%22%20repo%3Afacebook%2Freact
}
    if (node.tag === HostRoot) {
       T
       r
      return MOUNTED;
    }
     I
     t
    return UNMOUNTED;
  }
   This function is copied from React and should be kept in sync:
   https:github.com/facebook/react/blob/master/packages/react-reconciler/src/ReactFiberTreeReflection.js
   It would be nice if we updated React to inject this function directly (vs just indirectly via findDOMNode).
   BEGIN copied code
  function findCurrentFiberUsingSlowPathById(id: number): Fiber | null {
    const fiber = idToArbitraryFiberMap.get(id);
    if (fiber == null) {
      console.warn(`Could not find Fiber with id "${id}"`);
      return null;
    }
    const alternate = fiber.alternate;
    if (!alternate) {
       I
      const state = isFiberMountedImpl(fiber);
      if (state === UNMOUNTED) {
        throw Error('Unable to find node on an unmounted component.');
      }
      if (state === MOUNTING) {
        return null;
      }