bug: controller panics for default backend services.

[hbagdi]

Summary

If default backend is declared in an Ingress resource, the controller panics

Kong Ingress controller version

0.7.0
This is not a problem with 0.6.0

Kong or Kong Enterprise version

1.4.3

Kubernetes version

1.15

Environment

• Cloud provider or hardware configuration: GKE

Steps To Reproduce

echo "apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: test
spec:
  backend:
    serviceName: billing
    servicePort: 80
  tls:
  - hosts:
    - foo.com
    secretName: tls-secret" | kubectl apply -f -

The controller crashes due to a nil pointer reference.