fix(langfuse): guard against None standard_callback_dynamic_params

Fix AttributeError: 'NoneType' object has no attribute 'get' when Langfuse
is configured via environment variables (no per-request dynamic params).

In _dynamic_langfuse_credentials_are_passed() and
get_dynamic_langfuse_logging_config(), standard_callback_dynamic_params can
be None (not {}). Calling .get() directly on None raises AttributeError.

Fix: use params = standard_callback_dynamic_params or {} before calling .get().

Added regression tests for both functions to ensure None is handled correctly.

Fixes: BerriAI/litellm#25940

litellm/integrations/langfuse/langfuse_handler.py

@@ -140,13 +140,15 @@ class LangFuseHandler:
         If no dynamic parameters are provided, it uses the `globalLangfuseLogger` values
         """
         # only use dynamic params if langfuse credentials are passed dynamically
+        # Guard against None to handle the case where no per-request params are passed
+        params = standard_callback_dynamic_params or {}
         return LangfuseLoggingConfig(
-            langfuse_secret=standard_callback_dynamic_params.get("langfuse_secret")
-            or standard_callback_dynamic_params.get("langfuse_secret_key"),
-            langfuse_public_key=standard_callback_dynamic_params.get(
+            langfuse_secret=params.get("langfuse_secret")
+            or params.get("langfuse_secret_key"),
+            langfuse_public_key=params.get(
                 "langfuse_public_key"
             ),
-            langfuse_host=standard_callback_dynamic_params.get("langfuse_host"),
+            langfuse_host=params.get("langfuse_host"),
         )
 
     @staticmethod
@@ -159,12 +161,14 @@ class LangFuseHandler:
         Returns:
             bool: True if the dynamic langfuse credentials are passed, False otherwise
         """
+        # Guard against None to handle the case where no per-request params are passed (credentials come from env vars)
+        params = standard_callback_dynamic_params or {}
 
         if (
-            standard_callback_dynamic_params.get("langfuse_host") is not None
-            or standard_callback_dynamic_params.get("langfuse_public_key") is not None
-            or standard_callback_dynamic_params.get("langfuse_secret") is not None
-            or standard_callback_dynamic_params.get("langfuse_secret_key") is not None
+            params.get("langfuse_host") is not None
+            or params.get("langfuse_public_key") is not None
+            or params.get("langfuse_secret") is not None
+            or params.get("langfuse_secret_key") is not None
         ):
             return True
         return False

tests/logging_callback_tests/test_langfuse_dynamic_credentials.py

@@ -127,3 +127,36 @@ def test_langfuse_handler_accepts_secret_key_alias(monkeypatch):
     assert captured["allow_env_credentials"] is False
     assert captured["cached_service_name"] == "langfuse"
     assert captured["cached_logging_obj"] is logger
+
+
+def test_dynamic_langfuse_credentials_are_passed_handles_none(monkeypatch):
+    """Regression test: _dynamic_langfuse_credentials_are_passed must not crash when standard_callback_dynamic_params is None.
+
+    When Langfuse is configured via environment variables (no per-request dynamic params),
+    standard_callback_dynamic_params is None, not {}. The function must not raise
+    AttributeError: 'NoneType' object has no attribute 'get'.
+    """
+    monkeypatch.setenv("LANGFUSE_PUBLIC_KEY", "pk-test")
+    monkeypatch.setenv("LANGFUSE_SECRET_KEY", "sk-test")
+    monkeypatch.setenv("LANGFUSE_HOST", "https://langfuse.example")
+
+    # Should return False (no dynamic params passed), not raise AttributeError
+    result = LangFuseHandler._dynamic_langfuse_credentials_are_passed(None)
+    assert result is False
+
+
+def test_get_dynamic_langfuse_logging_config_handles_none(monkeypatch):
+    """Regression test: get_dynamic_langfuse_logging_config must not crash when standard_callback_dynamic_params is None.
+
+    When Langfuse is configured via environment variables, standard_callback_dynamic_params is None.
+    The function should return a config with None values (relying on env var fallback downstream).
+    """
+    monkeypatch.setenv("LANGFUSE_PUBLIC_KEY", "pk-test")
+    monkeypatch.setenv("LANGFUSE_SECRET_KEY", "sk-test")
+    monkeypatch.setenv("LANGFUSE_HOST", "https://langfuse.example")
+
+    # Should not raise AttributeError
+    config = LangFuseHandler.get_dynamic_langfuse_logging_config(None)
+    assert config.langfuse_public_key is None
+    assert config.langfuse_secret is None
+    assert config.langfuse_host is None