Error raised when trying to update a minimal service

[WTFKr0]

Description

When we create a service with minimal option by portainer api, we can't edit it by interface.
We got a js error :

Cannot read property 'Mode' of undefined

Steps to reproduce

• Create minimal service by api (name + image) :

curl -s -X POST <portainer_api>/endpoints/<endpoint_id>/docker/services/create' -H 'Accept: application/json' -H 'Authorization: Bearer <token>' -d '{"Name":"my_service","TaskTemplate":{"ContainerSpec":{"Image":"nginx:alpine"}}}'

• Try editing it by interface :
  Scale the service from portainer interface from 1 to 2

More info

For info the json of the service

{
    "CreatedAt": "2017-12-28T08:07:59.017847182Z",
    "Endpoint": {
        "Spec": {}
    },
    "ID": "930xg1kpzyy7utnczje8qvjyg",
    "Spec": {
        "Labels": {},
        "Mode": {
            "Replicated": {
                "Replicas": 1
            }
        },
        "Name": "my_service",
        "TaskTemplate": {
            "ContainerSpec": {
                "Image": "nginx:alpine"
            },
            "ForceUpdate": 0,
            "Runtime": "container"
        }
    },
    "UpdatedAt": "2017-12-28T08:07:59.017847182Z",
    "Version": {
        "Index": 10227
    }
}

What happen

Seems that the service object in updateService funtion is undefined