the function removeFacet clears $scope.currentSearch and then calls $scope.initFacets which resyncs currentSearch from the url.

magic_search.js does not add the search to the url so when you clear try to clear an individual facet all facets are removed. The demo adds an additional javascript file main.js which is not included with the module that updates the url after each facet is added. The url update could should be handled inside the module.