I’ve got an error when I tried to put volume statement at deployment.yaml and run helm upgrade.

UPGRADE FAILEDError: YAML parse error on what-the-helm/templates/deployment.yaml: error converting YAML to JSON: yaml: line 54: mapping values are not allowed in this contextError: UPGRADE FAILED: YAML parse error on what-the-helm/templates/deployment.yaml: error converting YAML to JSON: yaml: line 54: mapping values are not allowed in this context

My deployment.yaml looks like:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "what-the-helm.fullname" . }}
  labels:
{{ include "what-the-helm.labels" . | indent 4 }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app.kubernetes.io/name: {{ include "what-the-helm.name" . }}
      app.kubernetes.io/instance: {{ .Release.Name }}
  template:
    metadata:
      labels:
        app.kubernetes.io/name: {{ include "what-the-helm.name" . }}
        app.kubernetes.io/instance: {{ .Release.Name }}
    spec:
    {{- with .Values.imagePullSecrets }}
      imagePullSecrets:
        {{- toYaml . | nindent 8 }}
    {{- end }}
      serviceAccountName: {{ template "what-the-helm.serviceAccountName" . }}
      securityContext:
        {{- toYaml .Values.podSecurityContext | nindent 8 }}
      containers:
        - name: {{ .Chart.Name }}
          securityContext:
            {{- toYaml .Values.securityContext | nindent 12 }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - name: http
              containerPort: 80
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /
              port: http
          readinessProbe:
            httpGet:
              path: /
              port: http
          resources:
            {{- toYaml .Values.resources | nindent 12 }}
          volumeMounts:
            - name: nginx
              mountPath: /usr/share/nginx/html
      volumes:
        - name: nginx
            configMap:
              name: nginx-configmap
      {{- with .Values.nodeSelector }}
      nodeSelector:
        {{- toYaml . | nindent 8 }}
      {{- end }}
    {{- with .Values.affinity }}
      affinity:
        {{- toYaml . | nindent 8 }}
    {{- end }}
    {{- with .Values.tolerations }}
      tolerations:
        {{- toYaml . | nindent 8 }}
    {{- end }}