Description

This will let us get rid of patterns like

pub enum AcceptedErrors { /* ... */ }

that require explicit declaration of every error type that might be raised with ?.

Desired behavior/Acceptance criteria (returned value, expected error, performance expectations, etc.)

• cleaner Results/error handling

Completion checklist

• Before closing this task, review one by one the checklist available here: https://www.mediawiki.org/wiki/Abstract_Wikipedia_team/Definition_of_Done#Back-end_Task/Bug_completion_checklist