If you register without passing environments or environment_id params, it chooses the default environment but we forgot to put that in an array.

https://github.com/Katello/katello/blob/e7b32979a6946d2af2618dba789a0669946fa018/app/controllers/katello/api/rhsm/candlepin_proxies_controller.rb#L335

So it causes

NoMethodError: undefined method `each' for #<Katello::ContentViewEnvironment id: 2, name: "Library", label: "Library", cp_id: ...