### Bug report

When the DropDownTree control is added as a Form editor through the Editor() method, there is an ArgumentNullException "Value cannot be null. (Parameter 'key')".

### Reproduction of the problem

Attached is a demo that replicates the issue.

If the DropDownTree is defined outside of the Form, it is bound to the Model property as expected.

### Expected/desired behavior

The DropDownTree editor should bind to the Model property in the Form.

### Environment

* **Kendo UI version: 2022.1.412
* **jQuery version: 1.12.4
* **Browser:** [all]