Fixed #1355 - DataTable row group and resizable column not working together

src/components/datatable/DataTable.vue

@@ -1095,6 +1095,7 @@ export default {
             for (let child of children) {
                 for (let row of child.children) {
                     let resizeCell = row.children[colIndex];
+                    if (resizeCell) {
                         resizeCell.style.flex = '0 0 ' + newColumnWidth + 'px';
 
                         if (this.columnResizeMode === 'fit') {
@@ -1105,6 +1106,7 @@ export default {
                         }
                     }
                 }
+            }
         },
         bindColumnResizeEvents() {
             if (!this.documentColumnResizeListener) {