Debian 11 Bullseye 64bits

Installation instructions

Logs Download 
wget -qO- https://dl.packager.io/srv/crohr/blank-sinatra-app/key | sudo apt-key add -
sudo wget -O /etc/apt/sources.list.d/blank-sinatra-app.list \
  https://dl.packager.io/srv/crohr/blank-sinatra-app/dependabot/bundler/sinatra-2.2.3/installer/debian/11.repo
sudo apt-get update
sudo apt-get install blank-sinatra-app

Note: You might need to apt-get install wget apt-transport-https for the above instructions to work.