React PropTypes for window.open

Question

I have a page that opens a new window and sends a message with window.open and window.postMessage. All is well and good there, however, I am trying to get the PropType validation for the window working.

The error I am getting is:

Warning: Failed prop type: Invalid prop newWindow of type Window supplied to ButtonsObj, expected instance of Window.

The issue is the same as here, unfortunately the provided answer doesn't seem to work. How do I include window as a valid prop with PropTypes?

// From ButtonsObj component class
openInNewTabWPeriods() {
  const win = window.open('management/new_window', 'NewWindow');
  window.addEventListener('message', this.sendUUIDs, false);
  this.props.dispatch({
    type: 'NEW_WINDOW',
    win,
  });
}

ButtonsObj.propTypes = {
  newWindow: PropTypes.instanceOf(window.constructor).isRequired,
};

// from the reducer
initialState = { newWindow: window.window };

With the initialState, I've also tried null, but that gives the following warning:

Warning: Failed prop type: The prop newWindow is marked as required in ButtonsObj, but its value is null.