An error occurred when convert empty array to an object in 1.8.5

[hankei6km]

I'm trying to convert an array of API responce to an object with JSONata.
in many cases it works very well.
(JSONata is very powerful)

However, I get an error when I convert an empty array in JSONata 1.8.5.
(in 1.7.0 work as expected)

Key in object structure must evaluate to a string; got: undefined

steps to reproduce

I tried it with JSONata Exerciser.

array to object

It works in the following cases.

https://try.jsonata.org/uvEJnSWm-

jsonata: $${id:{"label":label,"value":value}}

json:

[
  {
    "id": "abc",
    "label": "ABC",
    "value": 123
  },
  {
    "id": "def",
    "label": "DEF",
    "value": 321
  }
]

result:

{
  "abc": {
    "label": "ABC",
    "value": 123
  },
  "def": {
    "label": "DEF",
    "value": 321
  }
}

empty array

An error occurred when json was an empty array.
https://try.jsonata.org/r9UY9cPmx
(in 1.7.0 work as expected)

json:

[]

result (1.8.5):

Key in object structure must evaluate to a string; got: undefined

result (1.7.0):

{}

workaround

The following query works even with an empty array

$count($$) > 0 ? $${id:{"label":label,"value":value}} : {}

[hankei6km]

Additional Information.

In "1.8.0 - 1.8.4" worked as expected.

steps to reproduce

$ node --version
v14.18.1

import jsonata from 'jsonata';

const data = [];
try {
  const expression = jsonata('$${id:{"label":label,"value":value}}');
  console.log(
    `result => ${JSON.stringify(expression.evaluate(data), null, '  ')}`
  );
} catch (err) {
  console.log(`err => ${err.message}`);
}

1.8.0 - 1.8.4

result => {}

1.8.5

err => Key in object structure must evaluate to a string; got: undefined

[andrew-coleman]

Resolved by #555

[asampal]

Doesn't this warrant a new release?

[mattbaileyuk]

@asampal 1.8.6 was released today with this fix (among others)