### Bug report

When the Grid is grouped by a specified column, and this column has a "groupFooterTemplate" that contains aggregates from other fields, it cannot be exported to Excel. It throws a JavaScript exception.

### Reproduction of the problem

1) Group the Grid by the column "ProductName".

2) Export it to Excel through the built-in command "Export to Excel".

3) JS exception is thrown.

A Dojo sample for reproduction: https://dojo.telerik.com/UyUruyOZ

### Expected/desired behavior

The Excel export should work as expected when the Grid is grouped.

### Environment

* **Kendo UI version: 2022.2.802
* **jQuery version: 1.12.4
* **Browser: [all]