Angular 5 - custom properties panel

I have a problem when I build for production environment with angular-cli (ng build --prod),
please find console error image attached.
Version of bpmn-js 0.26.3, bpmn-js-properties-panel 0.19.1
Problem is due to initialization of custom properties panel, when I remove the below part of of code, problem is not present and of course also the custom properties on panel.

const customPropertiesProviderModule = {
  __init__: ['propertiesProvider'],
  propertiesProvider: ['type', CustomPropertiesProvider]

When I do development build (ng serve), no problems occurs.
I think that problem is related to code minification, but I can’t understand how to resolve. Can someone help me?


Even I am facing same issue, @bpmnNat could you find any fix for this?