In MW REST API we've started prefixing all the error message keys with the endpoint name, like rest-pagehistory-revision-nonexistent. However, a lot of messages are the same for all the endpoints, so I propose to deduplicate them and pull out the endpoint name prefix when it's not needed. That way we can have less messages and reuse translations created for one endpoint in another.
Customize query in gerrit
|mediawiki/core||master||+115 -158||REST: Deduplicate and normalize REST error message names|