<!--
  Note: if the issue is about documentation or the website, please file it at:
  https://github.com/reactjs/reactjs.org/issues/new
-->

**Do you want to request a *feature* or report a *bug*?**

bug.

**What is the current behavior?**

```js
  renderer.create(
    <Fragment>
      <Fragment>foo</Fragment>
    </Fragment>
  )
  .toTree()
```

> Invariant Violation: toTree() does not yet know how to handle nodes with tag=10

https://codesandbox.io/s/olky92m01y

**What is the expected behavior?**

returns a tree.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**

16.2.0

},
      getInstance() {
        if (root == null || root.current == null) {
          return null;
        }
        return TestRenderer.getPublicRootInstance(root);
      },
    };
    Object.defineProperty(
      entry,
      'root',
      ({
        configurable: true,
        enumerable: true,
        get: function() {
          if (root === null || root.current.child === null) {
            throw new Error("Can't access .root on unmounted test renderer");
          }
          return wrapFiber(root.current.child);
        },
      }: Object),
    );
    return entry;
  },
  
  unstable_batchedUpdates: batchedUpdates,
  
};
export default ReactTestRendererFiber;