RFC9535. NEsted Existens operator bug

[besok]

Issue: 8 in the filtered_cases.json

The bug is connected how we handle the existence operator.

[ArsalLivoroi]

This does not seem to be specific to nesting. The non-nested case fails too:

let json = json!({
  "a": {
    "empty_array": {"b": []},
    "empty_object": {"b": {}},
    "empty_string": {"b": ""},
    "no_b": {"c": 1}
  }
});
js_path("$.a[?@.b]", &json)   // returns [] instead of the first three

There look to be two separate problems here:

1. the existence test inspects the value of the node instead of the emptiness
   of the nodelist, so empty containers are treated as absent. PR Make the existence test depend on the nodelist, not on node values #117.

2. a filter selector applied directly to @ produces nothing, which is what
   keeps filter, nested red. $[?@[0]], $[?@[*]] and $[?@.v[?@>1]] all
   work; only $[?@[?@>1]] does not.

The PR fixes the first and leaves filter, nested failing.

[besok]

Thank you. Yeah, I did not test that so make total sense. Thanks for fixing one part of it. I am going to review it in a couple of days