fix(proxy): keep failing requests on keys with non-object logging metadata

A key whose stored metadata.logging is not a list of objects failed every
request with a 500 before this branch. The credential reference rewrite
turned those values into no entries, so the request quietly succeeded
without the key's logging. Raise a TypeError for those shapes again so the
request path behaves as it did on main, while empty values and objects with
unknown fields still go through the existing skip.

litellm/proxy/common_utils/callback_utils.py

@@ -750,11 +750,14 @@ def key_logging_entries(metadata: object) -> tuple[Mapping[str, object], ...] |
     entries: Final = decrypted_logging_entries(metadata)
     if entries is None:
         return None
-    return tuple(
-        resolved
-        for entry in object_sequence(entries) or ()
-        if (resolved := _with_credential(string_keyed(entry))) is not None
-    )
+    return tuple(resolved for entry in _logging_objects(entries) if (resolved := _with_credential(entry)) is not None)
+
+
+def _logging_objects(entries: object) -> tuple[Mapping[str, object], ...]:
+    items: Final = () if entries in ("", {}) else object_sequence(entries)
+    if items is None or not all(isinstance(item, Mapping) for item in items):
+        raise TypeError(f"key metadata.logging must be a list of objects, got {type(entries).__name__}")
+    return tuple(string_keyed(item) for item in items)
 
 
 def _with_credential(entry: Mapping[str, object]) -> Mapping[str, object] | None:

tests/unit/proxy/common_utils/test_callback_utils.py

@@ -848,3 +848,35 @@ def test_key_logging_entries_drops_an_entry_whose_credential_is_not_defined(monk
     ]
 
     assert key_logging_entries({"logging": entries}) == (kept,)
+
+
+@pytest.mark.parametrize(
+    "logging_value",
+    [
+        pytest.param("abc", id="string"),
+        pytest.param({"callback_name": "arize"}, id="object"),
+        pytest.param(5, id="number"),
+        pytest.param(["x"], id="list-with-string"),
+        pytest.param([{"callback_name": "langfuse", "callback_vars": {}}, None], id="list-with-null"),
+    ],
+)
+def test_key_logging_entries_fails_on_non_object_logging_like_the_request_path_always_has(
+    logging_value: object,
+) -> None:
+    with pytest.raises(TypeError):
+        key_logging_entries({"logging": logging_value})
+
+
+@pytest.mark.parametrize(
+    ("logging_value", "expected"),
+    [
+        pytest.param("", (), id="empty-string"),
+        pytest.param({}, (), id="empty-object"),
+        pytest.param([], (), id="empty-list"),
+        pytest.param([{"bad": 1}], ({"bad": 1},), id="object-with-unknown-fields"),
+    ],
+)
+def test_key_logging_entries_passes_empty_and_object_entries_through(
+    logging_value: object, expected: tuple[dict[str, object], ...]
+) -> None:
+    assert key_logging_entries({"logging": logging_value}) == expected