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/network/collator-protocol/src/lib.rs

@@ -17,7 +17,8 @@
 //! The Collator Protocol allows collators and validators talk to each other.
 //! This subsystem implements both sides of the collator protocol.
 
-#![deny(missing_docs, unused_crate_dependencies)]
+#![deny(missing_docs)]
+#![deny(unused_crate_dependencies)]
 #![recursion_limit = "256"]
 
 use std::time::Duration;
@@ -39,7 +40,6 @@ use polkadot_subsystem::{
 };
 
 mod error;
-use error::{FatalResult, Result};
 
 mod collator_side;
 mod validator_side;
@@ -98,7 +98,7 @@ impl CollatorProtocolSubsystem {
 		Self { protocol_side }
 	}
 
-	async fn run<Context>(self, ctx: Context) -> FatalResult<()>
+	async fn run<Context>(self, ctx: Context) -> std::result::Result<(), error::FatalError>
 	where
 		Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
 		Context: SubsystemContext<Message = CollatorProtocolMessage>,