fatality based errors (#4448)

* seed commit for fatality based errors

* fatality

* first draft of fatality

* cleanup

* differnt approach

* simplify

* first working version for enums, with documentation

* add split

* fix simple split test case

* extend README.md

* update fatality impl

* make tests passed

* apply fatality to first subsystem

* fatality fixes

* use fatality in a subsystem

* fix subsystemg

* fixup proc macro

* fix/test: log::*! do not execute when log handler is missing

* fix spelling

* rename Runtime2 to something sane

* allow nested split with `forward` annotations

* add free license

* enable and fixup all tests

* use external fatality

Makes this more reviewable.

* bump fatality dep

Avoid duplicate expander compilations.

* migrate availability distribution

* more fatality usage

* chore: bump fatality to 0.0.6

* fixup remaining subsystems

* chore: fmt

* make cargo spellcheck happy

* remove single instance of `#[fatal(false)]`

* last quality sweep

* fixup

polkadot/node/subsystem-util/src/runtime/mod.rs

@@ -44,7 +44,7 @@ use crate::{
 mod error;
 
 use error::{recv_runtime, Result};
-pub use error::{Error, Fatal, NonFatal};
+pub use error::{Error, FatalError, JfyiError};
 
 /// Configuration for construction a `RuntimeInfo`.
 pub struct Config {
@@ -169,7 +169,7 @@ impl RuntimeInfo {
 			let session_info =
 				recv_runtime(request_session_info(parent, session_index, sender).await)
 					.await?
-					.ok_or(NonFatal::NoSuchSession(session_index))?;
+					.ok_or(JfyiError::NoSuchSession(session_index))?;
 			let validator_info = self.get_validator_info(&session_info).await?;
 
 			let full_info = ExtendedSessionInfo { session_info, validator_info };