Ah, another issue....not sure what this means...
[update] opened a fresh terminal window and retyped the command and now it seems OK. Process is running and command issued successfully.
But now when trying to set up so that Assistant-relay starts every time the RPi boots, I get the terminal window hanging at this....
I've done a reboot and tried again but it hangs at the same point. Very exciting install this
[Update] finally got npm to complete. Seems many people have issue. I found these 2 references helpful...
Specifically, clearing the proxy settings...
npm config delete http-proxy
npm config delete https-proxy
npm config rm proxy
npm config rm https-proxy
Setting the maximum sockets...
npm set maxsockets 3
Splitting the command into 2 lines...
npm install -g pm2
And trying the 1st line until eventually all the files were loaded into cache and then I could complete the install successfully with the 2nd line.
That was interesting
Anyway, hope my notes help someone in the future. Keep at it - eventually you will get it to work!