Bpmn-js-differ errors

Hello I try to extend my current properties-panel modeler with bpmn-js-differ. I downloaded npm install --save bpmn-js-differ and npm install --save bpmn-moddle I created a folder name bpmn-js-differ and put all of the necessary files in there including change-handler.js. Can anybody tell me what I’m doing wrong? One of the error Uncaught Error: Cannot find module '../bpmn-js-differ/app/change-handler' but I have that file in there already.26

Can you please share a code example? How do you bootstrap your application?