<!-- Please answer both questions below before submitting this issue. -->

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

Please provide a link to the URL of the website (if it is public), a CodeSandbox (https://codesandbox.io/s/new) example that reproduces the bug, or a project on GitHub that we can checkout and run locally.

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

If possible, please describe how to reproduce this bug on the website or app mentioned above:
1. <!-- FILL THIS IN -->
2. <!-- FILL THIS IN -->
3. <!-- FILL THIS IN -->

<!--------------------------------------------------->
<!-- Please do not remove the text below this line -->
<!--------------------------------------------------->

### Generated information

DevTools version: 4.13.1-93782cfed2

Call stack:
(none)

Component stack:
(none)

GitHub URL search query:
https://api.github.com/search/issues?q=Cannot%20add%20node%20%20because%20a%20node%20with%20that%20id%20is%20already%20in%20the%20Store.%20in%3Atitle%20is%3Aissue%20is%3Aopen%20is%3Apublic%20label%3A%22Component%3A%20Developer%20Tools%22%20repo%3Afacebook%2Freact
} else {
         The 
         def
         whi
        
         Sea
        let didFindChild = false;
        let child = parentA.child;
        while (child) {
          if (child === a) {
            didFindChild = true;
            a = parentA;
            b = parentB;
            break;
          }
          if (child === b) {
            didFindChild = true;
            b = parentA;
            a = parentB;
            break;
          }
          child = child.sibling;
        }
        if (!didFindChild) {
           Sea
          child = parentB.child;
          while (child) {
            if (child === a) {
              didFindChild = true;
              a = parentB;