Description of problem:

In new PF5 Administer -> Settings, when I fill some data in a field that fail validation and confirm, I get an error message "Error updating setting: undefined" instead of a meaningful error message that would tell me I entered incorrect data and what data is expected.

How reproducible:

Deterministic

Is this issue a regression from an earlier version:

Yes, previous Satellite versions handled this better, although the error message was still weird, in 6.17 I got "Error updating setting: malformed format string - %(" - and that's still being shown in production.log

Steps to Reproduce:

1. Have a Satellite with PF5 Settings

2. Administer -> Settings

3. Fill "Entries per page" = "asf", confirm

Actual behavior:
Meaningless error message

Expected behavior:
An error message that tells me data failed validation and what was expected