fix(logging): stop noisy LocalProxy-not-mapped warning for guest users (#42306)

Co-authored-by: Claude <noreply@anthropic.com>

superset/utils/log.py

@@ -28,6 +28,7 @@ from typing import Any, Callable, cast, Literal
 
 from flask import g, has_request_context, request
 from flask_appbuilder.const import API_URI_RIS_KEY
+from sqlalchemy import inspect as sa_inspect
 from sqlalchemy.exc import SQLAlchemyError
 
 from superset.extensions import stats_logger_manager
@@ -193,11 +194,14 @@ class AbstractEventLogger(ABC):
         if user_id is None and has_request_context():
             try:
                 actual_user = g.get("user", None)
-                if actual_user is not None:
+                # Guest/anonymous users (e.g. embedded dashboards) are never
+                # DB-mapped, so adding them to the session always fails.
+                # This is expected and not worth logging.
+                if actual_user is not None and sa_inspect(actual_user, raiseerr=False):
                     db.session.add(actual_user)
                     user_id = get_user_id()
             except Exception as ex:
-                logging.warning("Failed to add user to db session: %s", ex)
+                logger.debug("Failed to add user to db session: %s", ex)
                 user_id = None
         payload = collect_request_payload()
         if object_ref: