fix(app_dsl_service): handle missing app mode with a ValueError (#11945)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/services/app_dsl_service.py

     ) -> App:
         """Create a new app or update an existing one."""
         app_data = data.get("app", {})
-        app_mode = AppMode(app_data["mode"])
+        app_mode = app_data.get("mode")
+        if not app_mode:
+            raise ValueError("loss app mode")
+        app_mode = AppMode(app_mode)
 
         # Set icon type
         icon_type_value = icon_type or app_data.get("icon_type")