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];
```

}
      }
    }
    invariant(
      container.nodeType !== DOC_NODE_TYPE,
      'You\'re trying to render a component to the document but ' +
        'you didn\'t use server rendering. We can\'t do this ' +
        'without using server rendering due to cross-browser quirks. ' +
        'See ReactDOMServer.renderToString() for server rendering.'
    );
    if (transaction.useCreateElement) {
      while (container.lastChild) {
        container.removeChild(container.lastChild);
      }
      DOMLazyTree.insertTreeBefore(container, markup, null);
    } else {
      setInnerHTML(container, markup);
      ReactDOMComponentTree.precacheNode(instance, container.firstChild);
    }
    if (__DEV__) {
      ReactInstrumentation.debugTool.onNativeOperation(
        ReactDOMComponentTree.getInstanceFromNode(container.firstChild)._debugID,
        'mount',
        markup.toString()
      );
    }
  },
};
module.exports = ReactMount;