I fixed the Cannot read property publicRoutes of undefined error in our git master branch, but I'm afraid its unrelated.
The publicAccessEnabled exposes the assets to the public if you use jsreport authentication extension.
I believe you don't have it enabled. So this won't help anyway.
The problem could be what you set to the extensions_assets_rootUrlForLinks.
This URL is used from inside of the docker container to reach the jsreport server.
This means the port should be the local one 5488.