Unable to create if else condition in config

[edaena]

Describe the bug:
Unable to create if else condition in config.

To Reproduce:
Add an if condition like the one in the selector below:

apiVersion: v1
kind: Service
metadata:
  name: {{ .Values.appName }}-svc-stage
spec:
  type: ClusterIP
  selector:
    app: {{ .Values.appName }}
    {{- if eq .Values.productionSlot "blue" }}
    slot: green
    {{- else }}
    slot: blue
    {{- end }}

Expected behavior:
The correct files are generated

Seen:

ERRO[26-04-2019 15:13:14] helm template failed with: Error: render error in "service-chart/templates/service-stage.yaml": template: service-chart/templates/service-stage.yaml:9:11: executing "service-chart/templates/service-stage.yaml" at <eq .Values.productio...>: error calling eq: invalid type for comparison

Additional context:
Bug encountered as part of the work to enable blue-green deployment for project jackson: project-jackson/service-stage.yaml