fix(litellm_pre_call_utils.py): fix return statement

Author: krrishdholakia

litellm/proxy/litellm_pre_call_utils.py

@@ -623,6 +623,8 @@ def add_management_endpoint_metadata_to_request_metadata(
 
         ignore any sensitive fields like logging, api_key, etc.
         """
+        if _metadata_variable_name not in data:
+            return data
         from litellm.proxy._types import (
             LiteLLM_ManagementEndpoint_MetadataFields,
             LiteLLM_ManagementEndpoint_MetadataFields_Premium,