very elegant extension API and parts of it used in std as POC

orchid-extension/src/proj_error.rs

@@ -0,0 +1,18 @@
+//! Abstractions for handling various code-related errors under a common trait
+//! object.
+
+use std::any::Any;
+use std::borrow::Cow;
+use std::cell::RefCell;
+use std::sync::Arc;
+use std::{fmt, iter};
+
+use dyn_clone::{clone_box, DynClone};
+use itertools::Itertools;
+use orchid_api::error::{ProjErr, ProjErrLocation};
+
+use crate::boxed_iter::{box_once, BoxedIter};
+use crate::intern::{deintern, intern, Token};
+use crate::location::{GetSrc, Position};
+#[allow(unused)] // for doc
+use crate::virt_fs::CodeNotFound;