Add test for _walk_for_ref non-dict/non-list branch coverage

Author: koxudaxi

tests/parser/test_jsonschema.py

@@ -1152,6 +1152,9 @@ def test_walk_for_ref_with_list_data() -> None:
     # Test list with non-dict items
     result = parser._walk_for_ref([1, "string", None], "#/$defs/Target", set())
     assert result is False
+    # Test with non-dict, non-list data (e.g. a string)
+    result = parser._walk_for_ref("just a string", "#/$defs/Target", set())
+    assert result is False
 
 
 def test_walk_for_ref_invalid_resolve_ref() -> None: