A Novel Look at Error Handling in Rust

I wrote about the idea of “warning errors” before in recapping an Oxide and Friends episode https://www.schneems.com/2025/03/26/a-daft-procmacro-trick-how-to-emit-partialcode-errors/.

I recently experimented with a few different ways to represent - return that emits multiple success and error values. https://github.com/heroku/docker-heroku-ruby-builder/pull/155.

One annoying issue with multi errors in general is lack of a "non empty vec" to prevent constructing and returning an empty vec (in situations where you want to communicate "if it's there it means there was a problem".