fix: avoid panic on empty list LABEL_LIST filters

python/python/tests/test_scalar_index.py

@@ -2054,6 +2054,25 @@ def test_label_list_index_array_contains(tmp_path: Path):
     assert "ScalarIndexQuery" not in explain
 
 
+def test_label_list_index_empty_list_filters(tmp_path: Path):
+    """Empty list filters should not panic and should match pre-index results."""
+    tbl = pa.table({"labels": [["foo"], ["bar"], ["foo", None], [None], [], None]})
+    dataset = lance.write_dataset(tbl, tmp_path / "dataset")
+
+    filters = [
+        "array_has_any(labels, [])",
+        "array_has_all(labels, [])",
+        "NOT array_has_all(labels, [])",
+        "NOT array_has_any(labels, [])",
+    ]
+    expected = {f: dataset.to_table(filter=f).num_rows for f in filters}
+
+    dataset.create_scalar_index("labels", index_type="LABEL_LIST")
+
+    for f in filters:
+        assert dataset.to_table(filter=f).num_rows == expected[f]
+
+
 def test_label_list_index_null_element_match(tmp_path: Path):
     """Covers NULL elements inside non-NULL lists (list itself is never NULL)."""
     tbl = pa.table(

rust/lance-index/src/scalar/expression.rs

@@ -513,6 +513,9 @@ impl ScalarQueryParser for LabelListQueryParser {
         let label_list = maybe_scalar(&args[1], data_type)?;
         if let ScalarValue::List(list_arr) = label_list {
             let list_values = list_arr.values();
+            if list_values.is_empty() {
+                return None;
+            }
             let mut scalars = Vec::with_capacity(list_values.len());
             for idx in 0..list_values.len() {
                 scalars.push(ScalarValue::try_from_array(list_values.as_ref(), idx).ok()?);