Error handling

Only on SAP S/4HANA 2023 and 2025, on premise or private cloud: [SAP S/4HANA Cloud, Public Edition](external:sap-s4hana-cloud-public-edition) and the [SAP BTP ABAP environment](artifact:btp-abap-environment) are listed as coming soon, and a 2023 system has to leave out `ZABAP_PRC_EVENTS_SE_2025`, whose event-based side effects rely on APIs released with S/4HANA 2025. Not for a system that already carries a copy, because object names are global and two versions cannot live side by side, and not for a productive system by way of the `ZABAP_PRC_DEMO*` packages, which the README states are not intended for one and whose init classes delete and rebuild their own tables on every run. While the major version is 0 the public API is not stable: minor bumps carry breaking changes with no deprecation period, so productive use means pinning a tag and reading the CHANGELOG before every upgrade.