BUG: json object parse index failure

[dentiny]

Hi team, I found this issue when I'm using lance

>>> import lance, pyarrow as pa, json
>>> arr_data = [json.dumps(["zero", "one", "two"])]
>>> obj_data = [json.dumps({"0": "from_object"})]
>>> table = pa.table({
...     "id": [1, 2],
...     "data": pa.array(arr_data + obj_data, type=pa.json_()),
... })
>>> lance.write_dataset(table, "/tmp/test_json_key", mode="overwrite")
[2026-04-28T06:07:16Z WARN  lance::dataset::write::insert] No existing dataset at /tmp/test_json_key, it will be created
<lance.dataset.LanceDataset object at 0x12aa1ebd0>
>>> ds = lance.dataset("/tmp/test_json_key")
>>> result = ds.to_table(filter="json_get_string(data, '0') = 'from_object'")
>>> print(f"Object field '0' match: {result.num_rows}")
Object field '0' match: 0

I expect the matched row count should be 1, instead of 0

An example that works as expected

>>> import lance, pyarrow as pa, json
>>> arr_data = [json.dumps(["zero", "one", "two"])]
>>> obj_data = [json.dumps({"hello": "from_object"})]
>>> table = pa.table({"id": [1, 2], "data": pa.array(arr_data + obj_data, type=pa.json_())})
>>> lance.write_dataset(table, "/tmp/test_json_key", mode="overwrite")
<lance.dataset.LanceDataset object at 0x106b2ebd0>
>>> ds = lance.dataset("/tmp/test_json_key")
>>> result = ds.to_table(filter="json_get_string(data, 'hello') = 'from_object'")
>>> print(f"Object field '0' match: {result.num_rows}")
Object field '0' match: 1