Server starts alright, nothing on the client page: Linux problem?

[frogeraie]

I followed carefully (twice on different Ubuntu machines) your HelloWorld instructions. The installation went alright and the server started as indicated by the "Server starting" message on the console.
francois@bernache:~$ bots-go -d /home/francois/p5/p5bots/hello/ server starting connected board object caught { board: 'arduino', port: '/dev/ttyACM1' } pin object caught { pin: 9, mode: 'digital', direction: 'output' } connected
But when I open the browser on localhost:8000 I get a blank screen with just the title "HELLO!" showing.
Is there a problem with Linux OS, I have Ubuntu 18.04?