The node-roon-api that version I posted was using was out of date and was causing an error this.moo.close is not a function which caused it to crash whenever I closed Roon. I updated the dependency and all seems to be working fine now. I’ve submitted a PR to @Boris_Pruessmann’s original github with these fixes. In the meantime, you can also use my fork here: GitHub - jcharr1/roon-extension-denon: Roon Volume Control Extension to control Denon & Marantz receivers
I also added a Docker image for it: Docker Hub