Vega Error - Node Not Found

Elastic Stack Kibana
1

I am getting an vega error Node Not Found XXX i dont know whats going on.

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "title": "Merchant Transaction Network",
  "width": 800,
  "height": 600,
  "autosize": "none",
  "data": [
    {
      "name": "merchant_transactions",
      "url": {
        "%context%": true,
        "%timefield%": "@timestamp",
        "index": "transactions*",
        "body": {
          "size": 0,
          "aggs": {
            "merchants": {
              "terms": {
                "field": "merchant_name.keyword",
                "size": 5,
                "min_doc_count": 1
              },
              "aggs": {
                "total_amount": {
                  "sum": {
                    "field": "transaction_amount"
                  }
                }
              }
            }
          }
        }
      },
      "format": {
        "property": "aggregations.merchants.buckets"
      }
    },
    {
      "name": "nodes",
      "source": "merchant_transactions",
      "transform": [
        {
          "type": "filter",
          "expr": "datum.key && datum.key !== ''"
        },
        {
          "type": "formula",
          "expr": "datum.key",
          "as": "id"
        },
        {
          "type": "formula",
          "expr": "abs(datum.total_amount.value) > 0 ? abs(datum.total_amount.value)/10 : 10",
          "as": "size"
        },
		{"type": "identifier", "as": "index"},
		{"type": "formula", "as": "index", "expr": "datum['index'] - 1"}
      ]
    },
    {
      "name": "links",
      "source": "merchant_transactions",
      "transform": [
        {
          "type": "filter",
          "expr": "datum.key && datum.key !== ''"
        },
        {
          "type": "formula",
          "expr": "datum.key",
          "as": "source"
        },
        {
          "type": "formula",
          "expr": "'Transactions'",
          "as": "target"
        },
        {
          "type": "lookup",
          "from": "final_nodes",
          "key": "id",
          "fields": ["source"],
          "as": ["source_node"]
        },
        {
          "type": "filter",
          "expr": "datum.source_node !== null"
        },
        {
          "type": "formula",
          "expr": "datum.total_amount.value > 0 ? datum.total_amount.value : 1",
          "as": "value"
        }
      ]
    }
  ],
  "marks": [
    {
      "type": "symbol",
      "from": {"data": "final_nodes"},
      "encode": {
        "enter": {
          "size": {"field": "size", "mult": 0.1},
          "fill": {"scale": "color", "field": "id"},
          "stroke": {"value": "#fff"},
          "strokeWidth": {"value": 1.5}
        }
      },
      "transform": [
        {
          "type": "force",
          "iterations": 300,
          "restart": true,
          "static": false,
          "signal": "force",
          "forces": [
            {"force": "center", "x": {"signal": "width / 2"}, "y": {"signal": "height / 2"}},
            {"force": "collide", "radius": 15},
            {"force": "link", "links": "links"}
          ]
        }
      ]
    },
    {
      "type": "path",
      "from": {"data": "links"},
      "encode": {
        "enter": {
          "stroke": {"value": "#aaa"},
          "strokeWidth": {"value": 1}
        }
      }
    }
  ],
  "scales": [
    {
      "name": "color",
      "type": "ordinal",
      "domain": {"data": "final_nodes", "field": "id"},
      "range": {"scheme": "category10"}
    }
  ]
}