This might be a reference to this one: https://github.com/facebook/react/issues/10212#issuecomment-346302374

The problem still exist.

So, trying to render with server side and got this error. I don't have this notation in my code but this might be a problem with dependencies.

```
TypeError: Cannot read property 'toLowerCase' of undefined
    at ReactDOMServerRenderer.renderDOM (/Users/lukasborawski/Dev/web-client/node_modules/react-dom/cjs/react-dom-server.node.development.js:2304:27)
...
```

```
"react": "^16.1.1",
"react-dom": "^16.2.0",
```

Thx for help.
);
        }
        const nextChildren = toArray(nextChild);
        const frame: Frame = {
          type: null,
          domNamespace: parentNamespace,
          children: nextChildren,
          childIndex: 0,
          context: context,
          footer: '',
        };
        if (__DEV__) {
          ((frame: any): FrameDev).debugElementStack = [];
        }
        this.stack.push(frame);
        return '';
      }
      
      const nextElement = ((nextChild: any): ReactElement);
      const elementType = nextElement.type;
      if (typeof elementType === 'string') {
        return this.renderDOM(nextElement, context, parentNamespace);
      }
      switch (elementType) {
        case REACT_FRAGMENT_TYPE: {
          const nextChildren = toArray(
            ((nextChild: any): ReactElement).props.children,
          );
          const frame: Frame = {
            type: null,