Error on line chart

[angiehjort]

Switch indicators to Poverty gap at 1.90
Select DK, DE, USA, Niger, unselect china and russia
Hit apply
Returns error
On refresh the error persists

{
  "name": "WaffleServerError",
  "message": "WS error",
  "details": "Too many query structure errors: \n* 'select.value' clause for 'datapoints' queries must have at least 1 item",
  "endpoint": "https://waffle-server.gapminder.org/api/ddf/ql",
  "url": "https://waffle-server.gapminder.org/api/ddf/ql?_language=en&from=datapoints&animatable=time&gapfill:true&select_key@=country&=time;&value@;;&where_$and@_country=$country;;;&join_$country_key=country&where_$and@_un/_state:true;&_country_$in@=nga&=dnk&=deu&=ner&=usa;;;;;;;&order/_by@=time",
  "ddfql": {
    "language": "en",
    "from": "datapoints",
    "animatable": "time",
    "gapfill": true,
    "select": {
      "key": [
        "country",
        "time"
      ],
      "value": []
    },
    "where": {
      "$and": [
        {
          "country": "$country"
        }
      ]
    },
    "join": {
      "$country": {
        "key": "country",
        "where": {
          "$and": [
            {
              "un_state": true
            },
            {
              "country": {
                "$in": [
                  "nga",
                  "dnk",
                  "deu",
                  "ner",
                  "usa"
                ]
              }
            }
          ]
        }
      }
    },
    "order_by": [
      "time"
    ]
  },
  "browserDetails": "Chrome 70 (70.0.3538.110)",
  "osName": "Mac/iOS",
  "homepoint": "https://www.gapminder.org/tools/#$state$time$value=2016;&marker$axis_y$data=data_wdi&which=si_pov_gaps&scaleType=linear&spaceRef:null;;;&chart-type=linechart",
  "time": "Fri Dec 28 2018 23:07:39 GMT+0100 (Central European Standard Time)"
}