message: fix :ref error
diff: @@ -30,7 +30,7 @@ export default class Popover extends Component {
  }
  this.eventTarget = null
  this.popperRef = React.createRef()
  - // this.referenceRef = React.createRef()
  + this.referenceRef = null
  }
  showPopper () {
  @@ -52,7 +52,7 @@ export default class Popover extends Component {
  isInPopover () {
  const popper = this.popperRef.current
  - const referenceRef = ReactDOM.findDOMNode(this.refs.referenceRef)
  + const referenceRef = ReactDOM.findDOMNode(this.referenceRef)
  const bool = !this.element || this.element.contains(this.eventTarget) ||
  !referenceRef || referenceRef.contains(this.eventTarget) ||
  !popper || popper.contains(this.eventTarget)
  @@ -64,7 +64,7 @@ export default class Popover extends Component {
  const { trigger } = this.props
  this.element = ReactDOM.findDOMNode(this)
  - const referenceRef = ReactDOM.findDOMNode(this.refs.referenceRef)
  + const referenceRef = ReactDOM.findDOMNode(this.referenceRef)
  // this.reference = ReactDOM.findDOMNode(this.refs.reference)
  if (referenceRef === null) return
  @@ -121,7 +121,7 @@ export default class Popover extends Component {
  return (
  <div className={classNames(className, 'hi-popover')} style={style} ref={node => { this.popoverContainer = node }}>
  - { React.cloneElement(React.Children.only(this.props.children), { ref: 'referenceRef', tabIndex: '0' }) }
  + { React.cloneElement(React.Children.only(this.props.children), { ref: (el) => { this.referenceRef = el }, tabIndex: '0' }) }
  <Popper
  className='hi-popover__popper'
  