This article addresses instance configurations with any Catalog Client Script containing g_form global methods, or some form of DOM manipulation in place, which are not supported in the Service Portal.
Prior to the Jakarta version, the errors were just logged in the browser console, and the user did not even notice them. However, starting from Jakarta, if there is a catalog client script error, the Service Portal displays an error alert, which is good for sysadmin debugging, but not for end-users.
These errors can be turned off using this system property "glide.sp.show_console_error" and setting it to false. This property does not remove the error from the browser console, however, it hides it from the UI.