Context variabe binding breaks when joining empty arrays or the join results in an empty result

[makeeno]

Let's consider the following input:

{
  "equipments": [
    {
      "type": "Type A",
      "name": "Name A"
    },
    {
      "type": "Type A",
      "name": "Name A2"
    },
    {
      "type": "Type B",
      "name": "Name B"
    }
  ],
  "data": [
    {
      "id": "0001",
      "equipmentName": "Name A"
    },
    {
      "id": "0001",
      "equipmentName": "Name A2",
      "value": 1
    },
    {
      "id": "0001",
      "equipmentName": "Name B",
      "value": 2
    },
    {
      "id": "0002",
      "equipmentName": "Name A",
      "value": 3
    },
    {
      "id": "0003",
      "equipmentName": "Name A2",
      "value": 3
    }
  ]
}

and the following Jsonata:

equipments@$equipments.data
  [$equipments.type = "Type A" and $equipments.name = equipmentName] {
  id: {
    "equipmentNames": equipmentName[]
  }
}

which correctly results in

{
  "0001": {
    "equipmentNames": [
      "Name A",
      "Name A2"
    ]
  },
  "0002": {
    "equipmentNames": [
      "Name A"
    ]
  },
  "0003": {
    "equipmentNames": [
      "Name A2"
    ]
  }
}

Now the issue is, if:

• in the input equipments is empty or does not exist
• or data is empty or does not exist
• or the filter [ ... ] (e.g. by changing "Type A" into "Type C") returns an empty result

then the following error is thrown:

can't access property "@", c is undefined

It looks like a bug since the error message is not clear about what I did wrong.

I could add a . after the filter but this changes the result and messes up the grouping:

equipments@$equipments.data
  [$equipments.type = "Type A" and $equipments.name = equipmentName]. {
  id: {
    "equipmentNames": equipmentName[]
  }
}