See this example: https://github.com/facebook/react/issues/11508#issuecomment-345464797.

I think it probably reflects a misunderstanding of how props and state work, and we should detect and warn if we see this.
render() {
        return <div />;
      }
    }
    const container = document.createElement('div');
    const instance = ReactDOM.render(<Component />, container);
    
    
    expect(instance.updater.isMounted(instance)).toBe(true);
    ReactDOM.unmountComponentAtNode(container);
    expect(instance.updater.isMounted(instance)).toBe(false);
  });
  it('warns if findDOMNode is used inside render', () => {
    class Component extends React.Component {
      state = {isMounted: false};
      componentDidMount() {
        this.setState({isMounted: true});
      }
      render() {