Cannot navigate in grouped Grid when scrollable is none

[mbechev]

Description

Having the following setup:

<kendo-grid
  [groupable]="true"
  [navigable]="true"
  scrollable="none"
>

breaks the navigation functionality, throwing the following error:

zone.js:163 Uncaught TypeError: Cannot read properties of undefined (reading 'rowIndex')
at NavigationCursor.offsetRow (progress-kendo-angular-grid.mjs:4348:28)
at NavigationCursor.moveDown (progress-kendo-angular-grid.mjs:4257:17)
at NavigationService6.onCursorKeydown (progress-kendo-angular-grid.mjs:5446:40)
at NavigationService6.onKeydown (progress-kendo-angular-grid.mjs:5648:12)
at Object.next (progress-kendo-angular-grid.mjs:5209:65)
at ConsumerObserver2.next (Subscriber.js:90:25)
at Subscriber2._next (Subscriber.js:59:22)
at Subscriber2.next (Subscriber.js:32:12)
at Subject.js:41:22
at errorContext (errorContext.js:23:5)

The issue is not reproduced when the scrollable isn't set or if the data is not grouped.

Steps To Reproduce

1. Focus the Name column header cell.
2. Click the down arrow.
3. The focus should be moved to the cell underneath, but the error is thrown then.

https://stackblitz.com/edit/angular-ade8zo?file=src%2Fapp%2Fapp.component.ts

Actual Behavior

The user is unable to focus some cells using the arrow keys due to the combination of groupable and non-scrollable Grid.

Expected Behavior

The user should be able to navigate through the cell without any issues.