Unable to install amp-paywall-demo

Hello,

I am trying to install and run your amp-paywall-demo: https://github.com/ampproject/samples/tree/master/amp-paywall-demo

I tried to follow the installation guide, and thus, I clones the repository (which worked fine), followed by `npm install` which unfortunately failed.

I tried to debug the error myself but was unable to do so.
I also googled the error, and searched for similar problems among the Issues in this repo, but that did not help either.

I created public gists with the output of the error, as well as the debug.log file
error: https://gist.github.com/rafaelmarques7/0b8c0da099fb53f00252b2d428f0ffd2
debug: https://gist.github.com/rafaelmarques7/707f1932f63cd042cdf1e6952c1093ab

I was hoping you can assists me with this soon, as my team is eager to use this service.

Much appreciated,
Rafael