According to the API documentation, the lack of a mask should result in a normal input of type `text` (http://www.telerik.com/kendo-angular-ui/components/inputs/api/MaskedTextBoxComponent/). I've tried empty string, not setting mask, having a mask of both null and undefined but nothing seems to work.
A simple plunker fork of your demo shows it breaking:
The error I receive is:
EXCEPTION: Error in ./MaskedTextBoxComponent class MaskedTextBoxComponent - inline template:1:8 caused by: Cannot read property 'test' of undefined
Also, is there another means to get a standard text input?