code: function($super, key, value, properties) {
              var keysToIgnore = {
                  'chart.nullValueMode': true
              };
  
              if(key in keysToIgnore) {
                  return;
              }
              $super(key, value, properties);
          }
docs: override point-based charts need to defensively ignore null-value mode, since 'connect' will lead to unexpected results