Ext version tested:
Ext 6.5.1.345 Modern, Ext 6.5.2.463 Modern


Browser versions tested against:
Windows7 Chrome 58.0.3029.110


Fiddle:
https://fiddle.sencha.com/#view/editor&fiddle/297e


When click the empty list, it throws an exception.
111.png


BTW, for Ext 6.5.0.775 Modern, it throws another error when mouse enter the list and mouse leave the list
222.png