### 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
```
) {
       If 
       No 
      
       The 
       (1) 
       (2) 
       Bec
       So 
      if (!isProfiling) {
        return;
      }
    }
    const numUnmountIDs =
      pendingRealUnmountedIDs.length +
      pendingSimulatedUnmountedIDs.length +
      (pendingUnmountedRootID === null ? 0 : 1);
    const operations = new Array(
       Ide
      2 +  [re
       How 
      1 +  [st
         The
        pendingStringTableLength +
         All 
         [TR
        (numUnmountIDs > 0 ? 2 + numUnmountIDs : 0) +
         Reg
        pendingOperations.length,
    );