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);
        continue;
      }
    }
    inst.props = element.props;
    inst.context = publicContext;
    inst.updater = updater;
    initialState = inst.state;
    if (initialState === undefined) {
      inst.state = initialState = null;
    }
    if (
      typeof inst.UNSAFE_componentWillMount === 'function' ||
      typeof inst.componentWillMount === 'function'
    ) {
      if (typeof inst.componentWillMount === 'function') {
        if (__DEV__) {
          if (
            warnAboutDeprecatedLifecycles &&
            inst.componentWillMount.__suppressDeprecationWarning !== true
          ) {
            const componentName = getComponentName(Component) || 'Unknown';
            if (!didWarnAboutDeprecatedWillMount[componentName]) {
              warning(
                false,
                '%s: componentWillMount() is deprecated and will be ' +
                  'removed in the next major version. Read about the motivations ' +
                  'behind this change: ' +
                  'https://fb.me/react-async-component-lifecycle-hooks' +
                  '\n\n' +