MachhineClass is invalid: nodeTemplate.zone in body must be of type string: "null"

[Ismail Alidzhikov]

/area quality
/kind bug
/kind regression
/platform azure

What happened:
After #417 Shoot fails to be created with:

  lastOperation:
    description: 'Flow "Shoot cluster reconciliation" encountered task errors: [task
      "Waiting until shoot worker nodes have been reconciled" failed: Error while
      waiting for Worker shoot--foo--azure-local/azure-local to become ready:
      error during reconciliation: Error reconciling worker: failed to deploy the
      machine classes: failed to apply manifests: 1 error occurred: could not apply
      object of kind "MachineClass" "shoot--foo--azure-local/shoot--foo--azure-local-cpu-worker-7d27e":
      MachineClass.machine.sapcloud.io "shoot--foo--azure-local-cpu-worker-7d27e"
      is invalid: nodeTemplate.zone: Invalid value: "null": nodeTemplate.zone in body
      must be of type string: "null"]'

What you expected to happen:
Shoot creation to work as expected.

How to reproduce it (as minimally and precisely as possible):

1. Create a non-zoned cluster

    infrastructureConfig:
      apiVersion: azure.provider.extensions.gardener.cloud/v1alpha1
      kind: InfrastructureConfig
      networks:
        vnet:
          cidr: 10.222.0.0/16
        workers: 10.222.0.0/16
      zoned: false

2. Make sure that the creation fails with the above error.

Anything else we need to know?:

Environment:

• Gardener version (if relevant):
• Extension version: e9c2d2b
• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration:
• Others:

[Himanshu Sharma]

@ialidzhikov did you try creating a non-zonal cluster? If yes , could you share the shoot yaml for the same

[Ismail Alidzhikov]

I now shared the infrastructureConfig in the issue description. I think that should be enough.