introduce errors with info (#1834)

polkadot/node/core/candidate-validation/Cargo.toml

@@ -5,11 +5,9 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 
 [dependencies]
-derive_more = "0.99.9"
 futures = "0.3.5"
-log = "0.4.8"
+log = "0.4.11"
 
-sp-blockchain = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-core = { package = "sp-core", git = "https://github.com/paritytech/substrate", branch = "master" }
 parity-scale-codec = { version = "1.3.0", default-features = false, features = ["bit-vec", "derive"] }
 

polkadot/node/core/candidate-validation/src/lib.rs

@@ -20,8 +20,11 @@
 //! according to a validation function. This delegates validation to an underlying
 //! pool of processes used for execution of the Wasm.
 
+#![deny(unused_crate_dependencies, unused_results)]
+#![warn(missing_docs)]
+
 use polkadot_subsystem::{
-	Subsystem, SubsystemContext, SpawnedSubsystem, SubsystemResult,
+	Subsystem, SubsystemContext, SpawnedSubsystem, SubsystemResult, SubsystemError,
 	FromOverseer, OverseerSignal,
 	messages::{
 		AllMessages, CandidateValidationMessage, RuntimeApiMessage,
@@ -116,9 +119,13 @@ impl<S, C> Subsystem<C> for CandidateValidationSubsystem<S> where
 	S: SpawnNamed + Clone + 'static,
 {
 	fn start(self, ctx: C) -> SpawnedSubsystem {
+		let future = run(ctx, self.spawn, self.metrics)
+			.map_err(|e| SubsystemError::with_origin("candidate-validation", e))
+			.map(|_| ())
+			.boxed();
 		SpawnedSubsystem {
 			name: "candidate-validation-subsystem",
-			future: run(ctx, self.spawn, self.metrics).map(|_| ()).boxed(),
+			future,
 		}
 	}
 }