Does "commandHandler.doKeyDown" avoids event listeners?

In my code I have a event listener,
this.goJsdiagram.addDiagramListener(“SelectionDeleted”, (e) => this.onSelectionDeleted(e) );
This does not work when I try to delete link on diagram with “delete” key.
This is happening after adding following part of code,
"this.goJsdiagram.commandHandler.doKeyDown = function () {
let e = this.diagram.lastInput;
if (e.key === ‘Backspace’) return;

It seems to me that your override of CommandHandler.doKeyDown is always a no-op. So it shouldn’t be surprising that it doesn’t do anything for the Backspace key.

As documented at CommandHandler | GoJS API :

This method may be overridden, but you should consider calling this base method in order to get all of its functionality. Please read the Introduction page on Extensions for how to override methods and how to call this base method.