message: correct EmojiPicker.ReactionPicker reactions PropType validity
diff: @@ -24,7 +24,7 @@ class ReactionPicker extends React.Component {
  mxEvent: PropTypes.object.isRequired,
  onFinished: PropTypes.func.isRequired,
  closeMenu: PropTypes.func.isRequired,
  - reactions: PropTypes.object.isRequired,
  + reactions: PropTypes.object,
  };
  constructor(props) {
  