Regression when using ExternalName services

[philpep]

After upgrade from chart 4.11.3 to 4.12.1 my ingresses using ExternalName services aren't working anymore (http 503 Service Temporarily Unavailable).

Logs of the controller shows:

2025/03/25 10:22:17 [error] 26#26: *33847 lua entry thread aborted: runtime error: /etc/nginx/lua/balancer.lua:78: bad argument #1 to 'ipairs' (table expected, got nil)
stack traceback:
coroutine 0:
        [C]: in function 'ipairs'
        /etc/nginx/lua/balancer.lua:78: in function 'resolve_external_names'
        /etc/nginx/lua/balancer.lua:114: in function 'sync_backend'
        /etc/nginx/lua/balancer.lua:148: in function </etc/nginx/lua/balancer.lua:146>, context: ngx.timer

Example:

apiVersion: v1
kind: Service
metadata:
  name: example
spec:
  type: ExternalName
  externalName: internal.example.com
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example.com
  annotations:
    kubernetes.io/ingress.class: "nginx"
    nginx.ingress.kubernetes.io/force-ssl-redirect: "true"
    nginx.ingress.kubernetes.io/backend-protocol: "HTTPS"
spec:
  rules:
    - host: example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: example
                port:
                  number: 443
  tls:
    - hosts:
      - example.com