code: function getCurrentType() {
      let currentType = storage.getDataByKey(savedChartTypeKey);
  
      if (!currentType) {
          currentType = charts[0];
          storage.setDataByKey(savedChartTypeKey, currentType);
      }
  
      return currentType;
  }
docs: Gets the current chart type either from the store or from the constants file
  If no chart type is found in the store, one is set from the constants.
  @return {String}     chart type