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.
render() {
              return {x: 123};
            }
          }
          await render(<ObjectComponent />, 1);
        },
        'Objects are not valid as a React child (found: object with keys {x}).' +
          (__DEV__
            ? ' If you meant to render a collection of children, use ' +
              'an array instead.'
            : ''),
      );
      itThrowsWhenRendering(
        'top-level object',
        async render => {
          await render({x: 123});
        },
        'Objects are not valid as a React child (found: object with keys {x}).' +
          (__DEV__
            ? ' If you meant to render a collection of children, use ' +
              'an array instead.'
            : ''),
      );
    });
  });
});