Nodejs-pptx works for PPTX and not for PPT

the following instruction

let newSlide = await pres.addSlide();

works for PPTX and for PPT gives the error
“Cannot read property ‘Relationships’ of undefined”

Environment:

  • OS: Windows 10.0.18363 N/A Build 18363
  • Node: 12.4.0
  • npm: 6.9.0
  • npm -v Nodejs-pptx
    6.9.0