fixed logic

src/extensions/group-by-v2/bootstrap-table-group-by.js

@@ -152,7 +152,7 @@ BootstrapTable.prototype.initBody = function (...args) {
 
       let formattedValue = item.name
 
-      if (!(that.options.groupByFormatter) === undefined) {
+      if (!(that.options.groupByFormatter === undefined)) {
         formattedValue = Utils.calculateObjectValue(item, that.options.groupByFormatter, [item.name, item.id, item.data])
       }
       html.push('<td',