fix(langfuse): guard against None standard_callback_dynamic_params

_dynamic_langfuse_credentials_are_passed() now returns False immediately
when standard_callback_dynamic_params is None, preventing the
AttributeError that caused all Langfuse success callbacks to silently
fail when credentials were supplied via environment variables.

Closes #25940

litellm/integrations/langfuse/langfuse_handler.py

@@ -86,9 +86,7 @@ class LangFuseHandler:
         if globalLangfuseLogger is not None:
             return globalLangfuseLogger
 
-        credentials_dict: Dict[
-            str, Any
-        ] = (
+        credentials_dict: Dict[str, Any] = (
             {}
         )  # the global langfuse logger uses Environment Variables, there are no dynamic credentials
         globalLangfuseLogger = in_memory_dynamic_logger_cache.get_cache(
@@ -160,6 +158,9 @@ class LangFuseHandler:
             bool: True if the dynamic langfuse credentials are passed, False otherwise
         """
 
+        if standard_callback_dynamic_params is None:
+            return False
+
         if (
             standard_callback_dynamic_params.get("langfuse_host") is not None
             or standard_callback_dynamic_params.get("langfuse_public_key") is not None

tests/test_litellm/integrations/langfuse/test_langfuse_handler.py

@@ -0,0 +1,39 @@
+from litellm.integrations.langfuse.langfuse_handler import LangFuseHandler
+
+
+class TestLangFuseHandlerDynamicCredentials:
+    def test_dynamic_credentials_none_returns_false(self):
+        """_dynamic_langfuse_credentials_are_passed should return False when
+        standard_callback_dynamic_params is None (env-var-only config)."""
+        result = LangFuseHandler._dynamic_langfuse_credentials_are_passed(None)
+        assert result is False
+
+    def test_dynamic_credentials_empty_dict_returns_false(self):
+        """_dynamic_langfuse_credentials_are_passed should return False when
+        standard_callback_dynamic_params is an empty dict."""
+        result = LangFuseHandler._dynamic_langfuse_credentials_are_passed({})
+        assert result is False
+
+    def test_dynamic_credentials_with_langfuse_host_returns_true(self):
+        result = LangFuseHandler._dynamic_langfuse_credentials_are_passed(
+            {"langfuse_host": "http://localhost:3000"}
+        )
+        assert result is True
+
+    def test_dynamic_credentials_with_public_key_returns_true(self):
+        result = LangFuseHandler._dynamic_langfuse_credentials_are_passed(
+            {"langfuse_public_key": "pk-lf-test"}
+        )
+        assert result is True
+
+    def test_dynamic_credentials_with_secret_key_returns_true(self):
+        result = LangFuseHandler._dynamic_langfuse_credentials_are_passed(
+            {"langfuse_secret_key": "sk-lf-test"}
+        )
+        assert result is True
+
+    def test_dynamic_credentials_with_secret_returns_true(self):
+        result = LangFuseHandler._dynamic_langfuse_credentials_are_passed(
+            {"langfuse_secret": "sk-lf-test"}
+        )
+        assert result is True