Follow up from https://github.com/facebook/react/pull/11616.

Here's one I found. These two invariants:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L330-L343

are in a function that's behind a DEV block:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L447-L449

I don't think this is intentional, but need to verify.

There may be more. I'll use this issue to track while https://github.com/facebook/react/pull/11616 preserves existing behavior.
state = 1234;
  render() {
    return React.createElement('span');
  }
}
class NullState extends React.Component {
  state = null;
  render() {
    return React.createElement('span');
  }
}
class BoundEventHandler extends React.Component {
  state = {
    bar: this.props.initialValue
  };
  handleClick = () => {
    this.setState({ bar: 'bar' });
  };
  render() {
    return (
      React.createElement(Inner, {
        name: this.state.bar,
        onClick: this.handleClick
      })
    );
  }
}
class UnboundEventHandler extends React.Component {