Maps and arrays could not be checked with nil pattern

[aescrob]

Kyverno CLI 1.14.2/1.14.4 and Kyverno Playground 1.14.2 Outputs PASS. Once deployed (v1.14.4), hundreds of messages are logged:

github.com/kyverno/kyverno/pkg/engine/pattern/pattern.go:133 Maps and arrays could not be checked with nil pattern

I am using a Test resource based on a helm chart wich renders a resource like this:

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-with-volume-null
spec:
  replicas: 3
  selector:
    matchLabels:
      app: deployment-with-volume-null
  template:
    metadata:
      labels:
        app: deployment-with-volume-null
    spec:
      containers:
      - name: nginx
        image: nginx
      volumes: null # this use case is due to malicious acm-chart template which sets volumes to null

Now i wanted to make the Kyverno Policy more robust like this (anyPattern):

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: validate-emptydir-sizelimit
  annotations:
    policies.kyverno.io/title: Validate required sizeLimit for emptyDir
    policies.kyverno.io/category: Other
    policies.kyverno.io/severity: audit
    policies.kyverno.io/subject: DaemonSet, Deployment, Job, StatefulSet
    policies.kyverno.io/description: >-
      DaemonSet, Deployment, Job and StatefulSet which mount emptyDir volumes may be allowed to potentially overrun the medium backing the emptyDir volume.
      This policy ensures that any emptyDir volume has a sizeLimit set.
spec:
  rules:
  - name: require-emptydir-sizelimit
    match:
      any:
      - resources:
          kinds:
          - DaemonSet
          - Deployment
          - Job
          - StatefulSet
    skipBackgroundRequests: true
    validate:
      failureAction: Audit
      allowExistingViolations: false
      message: "Audit Only: An emptyDir volumes must have sizeLimit set."
      anyPattern:
      - pattern:
        =(spec):
          =(template):
            =(spec):
              =(volumes):
              - =(emptyDir):
                  sizeLimit: "?*"
      - pattern:
        =(spec):
          =(template):
            =(spec):
              volumes: null

kyverno test:

apiVersion: cli.kyverno.io/v1alpha1
kind: Test
metadata:
  name: Test validate-emptydir-sizelimit
policies:
- ./policies/all_from_helm_template.yaml
resources:
- ./resources/validate_emptydir_sizelimit/deployment_with_volume_null.yaml
results:
- policy: validate-emptydir-sizelimit
  rule: require-emptydir-sizelimit
  resources: ["deployment-with-volume-null"]
  kind: Deployment
  result: pass

Tried to get rid of the message by changing the policy to volumes: "" - Kyverno Playground still says PASS, where as CLI fails.
Why do we have a different behaviour?
Is there another approach to catch this case?