Describe what you were doing when the bug occurred:
1. Clicking back to go back through the frames following a profile session. I think I got to zero and then clicked it again and then it errored

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DevTools version: 4.8.2-fed4ae024

Call stack: at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17661:26)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)
    at getCommitTree (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:17710:30)

Component stack: at CommitRankedAutoSizer (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:31963:48)
    at div
    at div
    at div
    at SettingsModalContextController (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:26139:23)
    at Profiler_Profiler (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:33363:48)
    at ErrorBoundary (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:27172:5)
    at PortaledContent (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:27303:32)
    at div
    at div
    at ProfilerContextController (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:30463:23)
    at TreeContextController (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:22538:23)
    at SettingsContextController (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:23040:27)
    at ModalDialogContextController (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:28328:23)
    at DevTools_DevTools (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:33797:21)
null, 
  ];
  const stringTableSize = operations[i++];
  const stringTableEnd = i + stringTableSize;
  while (i < stringTableEnd) {
    const nextLength = operations[i++];
    const nextString = utfDecodeString(
      (operations.slice(i, i + nextLength): any),
    );
    stringTable.push(nextString);
    i += nextLength;
  }
  while (i < operations.length) {
    const operation = operations[i];
    switch (operation) {
      case TREE_OPERATION_ADD:
        id = ((operations[i + 1]: any): number);
        const type = ((operations[i + 2]: any): ElementType);
        i += 3;
        if (nodes.has(id)) {
          throw new Error(
            `Commit tree already contains fiber "${id}". This is a bug in React DevTools.`,
          );
        }
        if (type === ElementTypeRoot) {
          i++; 
          i++; 
          if (__DEBUG__) {
            debug('Add', `new root fiber ${id}`);
          }