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.
}
    validateRenderResult(child, Component);
    if (typeof inst.getChildContext === 'function') {
      childContextTypes = Component.childContextTypes;
      if (typeof childContextTypes === 'object') {
        childContext = inst.getChildContext();
        for (contextKey in childContext) {
          invariant(
            contextKey in childContextTypes,
            '%s.getChildContext(): key "%s" is not defined in childContextTypes.',
            getComponentName(Component) || 'Unknown',
            contextKey,
          );
        }
      } else {
        warning(
          false,
          '%s.getChildContext(): childContextTypes must be defined in order to ' +
            'use getChildContext().',
          getComponentName(Component) || 'Unknown',
        );
      }
    }
    if (childContext) {
      context = Object.assign({}, context, childContext);
    }
  }
  return {child, context};
}
type Frame = {