getSlicerState error

I am trying to get a state from a slicer using getSlicerState but I am getting the error below:

TypeError: Cannot read property 'contract' of null
at e.getExploration (reportEmbed.slicer-api.min.js:1)
at e.tryGetVisualContainer (reportEmbed.slicer-api.min.js:1)
at e.<anonymous> (reportEmbed.slicer-api.min.js:1)
at reportEmbed.slicer-api.min.js:1
at Object.next (reportEmbed.slicer-api.min.js:1)
at reportEmbed.slicer-api.min.js:1
at new r (powerbiportal.dependencies.bundle.min.js:13)
at p (reportEmbed.slicer-api.min.js:1)
at e.handleSlicerRequest (reportEmbed.slicer-api.min.js:1)
at e.<anonymous> (reportEmbed.slicer-api.min.js:1)

This is my code:

this.report.getPages().then(pages => {
  let pageActive = pages.filter(page => page.isActive)
  if (pageActive[0]){
      pageActive[0].getVisuals().then(function(visuals) {
          console.log(visuals.filter(visual => visual.title === 'Basket'));
          visual = visuals.filter(visual => visual.title === 'Basket');
          visual[0].getSlicerState()
              .then(state => {
                console.log(state)
              });
      });
  }
});    

  Does anyone know what this issue is?

visual[0] is a VisualDescriptor. It is supposed to work straightaway.

Thanks

Thanks!