Spot the Error with this Replicaset, Selector Spec

vote-rs.yaml

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: vote
  labels:
    role: vote
spec:
  replicas: 4
  selector:
    matchLabels:
      app: python
      role: vote
    matchExpressions:
      key: version
      operator: Exists
  template:
    metadata:
      name: vote
      labels:
        app: python
        role: vote
        version: v2
    spec:
      containers:
        - name: app
          image: schoolofdevops/vote:v2
          resources:
            requests:
              memory: "64Mi"
              cpu: "50m"
            limits:
              memory: "128Mi"
              cpu: "250m"