Issue with persist columns demo

[Domamu]

Hi,

  I am trying the code for persist columns on my computer.  I got the code from this URL:

    https://www.telerik.com/kendo-angular-ui/components/knowledge-base/persist-columns-order/

  I received the error below when I tried to run the code:

Error: src/app/app.component.ts:52:16 - error TS7053: Element implicitly has an 'any' type because expression of type '"field"' can't be used to index type 'ColumnBase'.
  Property 'field' does not exist on type 'ColumnBase'.

52         field: col["field"],
                  ~~~~~~~~~~~~

  The corresponding code is this:

//the restructured columns containing only the needed properties that will be persisted
    const restructuredColumns: ColumnFooType[] = orderedColumns.map(col => {
      const column: ColumnFooType = {
        field: col["field"],
        title: col["title"]
      };
      return column;
    });

  It looks like there is no "field" property in ColumnBase.  Does anyone know how to fix the error?

Thanks,

Taichi