--- charts-original/templates/pvc.yaml
+++ charts/templates/pvc.yaml
@@ -16,12 +16,14 @@
   {{- end }}
 spec:
   accessModes:
+{{- $_ := required "Must provide at least one access mode for persistent volumes used by Grafana" .Values.persistence.accessModes }}
+{{- $_ := required "Must provide at least one access mode for persistent volumes used by Grafana" (first .Values.persistence.accessModes) }}
     {{- range .Values.persistence.accessModes }}
     - {{ . | quote }}
     {{- end }}
   resources:
     requests:
-      storage: {{ .Values.persistence.size | quote }}
+      storage: {{ required "Must provide size for persistent volumes used by Grafana" .Values.persistence.size | quote }}
   {{- if .Values.persistence.storageClassName }}
   storageClassName: {{ .Values.persistence.storageClassName }}
   {{- end -}}