message: Don't crash if scrollbars updated before init
  The initialisation here is done on a timer to allow the DOM
  elements to be in place before it's run, so it's possible for an
  update to happen ebfore the initialisation. Stop & bail out if
  there is no this.stickies.
diff: /*
  Copyright 2015, 2016 OpenMarket Ltd
  -Copyright 2017 Vector Creations Ltd
  +Copyright 2017, 2018 Vector Creations Ltd
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  @@ -451,6 +451,8 @@ module.exports = React.createClass({
  }
  }
  + if (!this.stickies) return;
  +
  const self = this;
  let scrollStuckOffset = 0;
  // Scroll to the passed in position, i.e. a header was clicked and in a scroll to state
  