Improve some relay errors readability

relays/client-substrate/src/client.rs

@@ -271,6 +271,10 @@ impl<C: Chain> Client<C> {
 			Ok(SubstrateChainClient::<C>::finalized_head(&*client).await?)
 		})
 		.await
+		.map_err(|e| Error::FailedToReadBestFinalizedHeaderHash {
+			chain: C::NAME.into(),
+			error: e.boxed(),
+		})
 	}
 
 	/// Return number of the best finalized block.
@@ -292,6 +296,7 @@ impl<C: Chain> Client<C> {
 			Ok(SubstrateChainClient::<C>::header(&*client, None).await?)
 		})
 		.await
+		.map_err(|e| Error::FailedToReadBestHeader { chain: C::NAME.into(), error: e.boxed() })
 	}
 
 	/// Get a Substrate block from its hash.
@@ -311,6 +316,11 @@ impl<C: Chain> Client<C> {
 			Ok(SubstrateChainClient::<C>::header(&*client, Some(block_hash)).await?)
 		})
 		.await
+		.map_err(|e| Error::FailedToReadHeaderByHash {
+			chain: C::NAME.into(),
+			hash: format!("{}", block_hash),
+			error: e.boxed(),
+		})
 	}
 
 	/// Get a Substrate block hash by its number.
@@ -394,10 +404,17 @@ impl<C: Chain> Client<C> {
 		storage_key: StorageKey,
 		block_hash: Option<C::Hash>,
 	) -> Result<Option<StorageData>> {
+		let cloned_storage_key = storage_key.clone();
 		self.jsonrpsee_execute(move |client| async move {
-			Ok(SubstrateStateClient::<C>::storage(&*client, storage_key, block_hash).await?)
+			Ok(SubstrateStateClient::<C>::storage(&*client, storage_key.clone(), block_hash)
+				.await?)
 		})
 		.await
+		.map_err(|e| Error::FailedToReadRuntimeStorageValue {
+			chain: C::NAME.into(),
+			key: cloned_storage_key,
+			error: e.boxed(),
+		})
 	}
 
 	/// Return native tokens balance of the account.
@@ -640,7 +657,14 @@ impl<C: Chain> Client<C> {
 		input: Input,
 		at_block: Option<C::Hash>,
 	) -> Result<Output> {
-		let encoded_output = self.state_call(method_name, Bytes(input.encode()), at_block).await?;
+		let encoded_output = self
+			.state_call(method_name.clone(), Bytes(input.encode()), at_block)
+			.await
+			.map_err(|e| Error::ErrorExecutingRuntimeCall {
+				chain: C::NAME.into(),
+				method: method_name,
+				error: e.boxed(),
+			})?;
 		Output::decode(&mut &encoded_output.0[..]).map_err(Error::ResponseParseFailed)
 	}
 

relays/client-substrate/src/error.rs

@@ -20,6 +20,7 @@ use bp_polkadot_core::parachains::ParaId;
 use jsonrpsee::core::Error as RpcError;
 use relay_utils::MaybeConnectionError;
 use sc_rpc_api::system::Health;
+use sp_core::storage::StorageKey;
 use sp_runtime::transaction_validity::TransactionValidityError;
 use thiserror::Error;
 
@@ -55,6 +56,52 @@ pub enum Error {
 	/// The client we're connected to is not synced, so we can't rely on its state.
 	#[error("Substrate client is not synced {0}.")]
 	ClientNotSynced(Health),
+	/// Failed to read best finalized header hash from given chain.
+	#[error("Failed to read best finalized header hash of {chain}: {error:?}.")]
+	FailedToReadBestFinalizedHeaderHash {
+		/// Name of the chain where the error has happened.
+		chain: String,
+		/// Underlying error.
+		error: Box<Error>,
+	},
+	/// Failed to read best finalized header from given chain.
+	#[error("Failed to read best header of {chain}: {error:?}.")]
+	FailedToReadBestHeader {
+		/// Name of the chain where the error has happened.
+		chain: String,
+		/// Underlying error.
+		error: Box<Error>,
+	},
+	/// Failed to read header by hash from given chain.
+	#[error("Failed to read header {hash} of {chain}: {error:?}.")]
+	FailedToReadHeaderByHash {
+		/// Name of the chain where the error has happened.
+		chain: String,
+		/// Hash of the header we've tried to read.
+		hash: String,
+		/// Underlying error.
+		error: Box<Error>,
+	},
+	/// Failed to execute runtime call at given chain.
+	#[error("Failed to execute runtime call {method} at {chain}: {error:?}.")]
+	ErrorExecutingRuntimeCall {
+		/// Name of the chain where the error has happened.
+		chain: String,
+		/// Runtime method name.
+		method: String,
+		/// Underlying error.
+		error: Box<Error>,
+	},
+	/// Failed to read sotrage value at given chain.
+	#[error("Failed to read storage value {key:?} at {chain}: {error:?}.")]
+	FailedToReadRuntimeStorageValue {
+		/// Name of the chain where the error has happened.
+		chain: String,
+		/// Runtime storage key
+		key: StorageKey,
+		/// Underlying error.
+		error: Box<Error>,
+	},
 	/// The bridge pallet is halted and all transactions will be rejected.
 	#[error("Bridge pallet is halted.")]
 	BridgePalletIsHalted,
@@ -81,16 +128,28 @@ impl From<tokio::task::JoinError> for Error {
 	}
 }
 
+impl Error {
+	/// Box the error.
+	pub fn boxed(self) -> Box<Self> {
+		Box::new(self)
+	}
+}
+
 impl MaybeConnectionError for Error {
 	fn is_connection_error(&self) -> bool {
-		matches!(
-			*self,
+		match *self {
 			Error::RpcError(RpcError::Transport(_))
 				// right now if connection to the ws server is dropped (after it is already established),
 				// we're getting this error
 				| Error::RpcError(RpcError::Internal(_))
 				| Error::RpcError(RpcError::RestartNeeded(_))
-				| Error::ClientNotSynced(_),
-		)
+				| Error::ClientNotSynced(_) => true,
+			Error::FailedToReadBestFinalizedHeaderHash { ref error, .. } => error.is_connection_error(),
+			Error::FailedToReadBestHeader { ref error, .. } => error.is_connection_error(),
+			Error::FailedToReadHeaderByHash { ref error, .. } => error.is_connection_error(),
+			Error::ErrorExecutingRuntimeCall { ref error, .. } => error.is_connection_error(),
+			Error::FailedToReadRuntimeStorageValue { ref error, .. } => error.is_connection_error(),
+			_ => false,
+		}
 	}
 }