I was testing latest refactor of PerfTools.
When using printOperations() often (but not always) I get 

```
Uncaught TypeError: Cannot read property 'displayName' of undefined
```

in getOperations() on the line:

```
var {displayName, ownerID} = treeSnapshot[instanceID];
```

typeof instance.unmountComponent === 'function',
      'Only React Components can be mounted.'
    );
  }
  
  
  
  instance._mountIndex = 0;
  instance._mountImage = null;
  if (__DEV__) {
    var debugID = isEmpty ? 0 : nextDebugID++;
    instance._debugID = debugID;
    var displayName = getDisplayName(instance);
    ReactInstrumentation.debugTool.onSetDisplayName(debugID, displayName);
    var owner = node && node._owner;
    if (owner) {
      ReactInstrumentation.debugTool.onSetOwner(debugID, owner._debugID);
    }
  }
  
  
  if (__DEV__) {
    if (Object.preventExtensions) {
      Object.preventExtensions(instance);
    }
  }
  return instance;
}
module.exports = instantiateReactComponent;