| Subject: | please amend the docs to make it clear that on_fail is not customizable at runtime |
As discussed on IRC, right now there is no sane way for an end user of formatters like https://metacpan.org/pod/DateTime::Format::MySQL to customize the on_fail.
While preferrably, that should be fixed, it would be much more kind on end users if the Builder documentation mentioned in a way that's very easy to spot, that customizing on_fail is basically impossible without copy-pasting an existing formatter.