Updating the webui seems to break it

I am following instructions here:

After I complete those steps, npm audit gives me warnings:
fixed 3 of 18 vulnerabilities in 575 scanned packages 4 vulnerabilities required manual review and could not be updated 1 package update for 11 vulnerabilities involved breaking changes (use 'npm audit fix --force' to install breaking changes; or refer to 'npm audit' for steps to fix these manually)

And the webui itself is missing variable declarations (my almost all the text is like {{ servers_up() }} and {{ host_heartbeat.uptime | seconds_to_time }} etc etc).

What did I do wrong?