### Describe what you were doing when the bug occurred:
1. I did profiling on a list, that gets updated on each pagination api call.
2. Once the profiling was done, I moved around in the Profiler to view the Flamegraph
3. Moving to second capture, the Profiler crashed.


**DevTools version**: 4.6.0-6cceaeb67

```
Component stack: in ec
    in div
    in div
    in div
    in So
    in Unknown
    in n
    in Unknown
    in div
    in div
    in rl
    in Ze
    in fn
    in Ga
    in _s
```
mountFiberRecursively(root.current, null, false, false);
        flushPendingEvents(root);
        currentRootID = -1;
      });
    }
  }
  function getUpdatersList(root): Array<SerializedElement> | null {
    return root.memoizedUpdaters != null
      ? Array.from(root.memoizedUpdaters).map(fiberToSerializedElement)
      : null;
  }
  function handleCommitFiberUnmount(fiber) {
     This is not recursive.
     We can't traverse fibers after unmounting so instead
     we rely on React telling us about each unmount.
    recordUnmount(fiber, false);
  }
  function handlePostCommitFiberRoot(root) {
    if (isProfiling && rootSupportsProfiling(root)) {
      if (currentCommitProfilingMetadata !== null) {
        const {effectDuration, passiveEffectDuration} = getEffectDurations(
          root,
        );
        currentCommitProfilingMetadata.effectDuration = effectDuration;
        currentCommitProfilingMetadata.passiveEffectDuration = passiveEffectDuration;
      }
    }
  }
  function handleCommitFiberRoot(root, priorityLevel) {
    const current = root.current;