message: Allows `onClose` to be optional within Overlay
diff: @@ -35,7 +35,7 @@ const Wrapper = styled.div`
  export default class Overlay extends PureComponent {
  static propTypes = {
  children: PropTypes.node.isRequired,
  - onClose: PropTypes.func.isRequired,
  + onClose: PropTypes.func,
  targetEl: PropTypes.func.isRequired,
  anchorY: PropTypes.oneOf(['top', 'bottom']),
  anchorX: PropTypes.oneOf(['left', 'right']),
  @@ -47,6 +47,7 @@ export default class Overlay extends PureComponent {
  }
  static defaultProps = {
  + onClose: () => {},
  anchorY: 'top',
  anchorX: 'left',
  alignToY: 'bottom',
  