Kamal should complain if proxy host contains invalid value

[a3kov]

I am proxying multiple hosts in Kamal. I had the old format in the config file:

proxy:
  ssl: true
  host: host1,host2,...

Kamal was happy to apply this, and SSL termination in Kamal-proxy was broken. After changing it to

proxy:
  ssl: true
  hosts:
    - host1
    - host2

SSL started to work. Kamal version: 2.2.2