improve error handling in cli (#7436)

* other error variant should carry a dyn Error

* introduce thiserror for error derive, add explicit error variants, cleanup dependencies

* cleanup handle dev-deps of sc-cli too

* Update client/cli/src/error.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

Co-authored-by: Bernhard Schuster <bernhard@parity.io>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/cli/src/commands/insert.rs

@@ -62,7 +62,7 @@ impl InsertCmd {
 	pub fn run(&self) -> Result<(), Error> {
 		let suri = utils::read_uri(self.suri.as_ref())?;
 		let base_path = self.shared_params.base_path.as_ref()
-			.ok_or_else(|| Error::Other("please supply base path".into()))?;
+			.ok_or_else(|| Error::MissingBasePath)?;
 
 		let (keystore, public) = match self.keystore_params.keystore_config(base_path)? {
 			KeystoreConfig::Path { path, password } => {
@@ -70,20 +70,19 @@ impl InsertCmd {
 					self.crypto_scheme.scheme,
 					to_vec(&suri, password.clone())
 				)?;
-				let keystore: SyncCryptoStorePtr = Arc::new(LocalKeystore::open(path, password)
-					.map_err(|e| format!("{}", e))?);
+				let keystore: SyncCryptoStorePtr = Arc::new(LocalKeystore::open(path, password)?);
 				(keystore, public)
 			},
 			_ => unreachable!("keystore_config always returns path and password; qed")
 		};
 
 		let key_type = KeyTypeId::try_from(self.key_type.as_str())
-			.map_err(|_| {
-				Error::Other("Cannot convert argument to keytype: argument should be 4-character string".into())
+			.map_err(|_e| {
+				Error::KeyTypeInvalid
 			})?;
 
 		SyncCryptoStore::insert_unknown(&*keystore, key_type, &suri, &public[..])
-			.map_err(|e| Error::Other(format!("{:?}", e)))?;
+			.map_err(|_| Error::KeyStoreOperation)?;
 
 		Ok(())
 	}

substrate/client/cli/src/commands/utils.rs

@@ -246,8 +246,7 @@ pub fn decode_hex<T: AsRef<[u8]>>(message: T) -> Result<Vec<u8>, Error> {
 	if message[..2] == [b'0', b'x'] {
 		message = &message[2..]
 	}
-	hex::decode(message)
-		.map_err(|e| Error::Other(format!("Invalid hex ({})", e)))
+	Ok(hex::decode(message)?)
 }
 
 /// checks if message is Some, otherwise reads message from stdin and optionally decodes hex

substrate/client/cli/src/commands/verify.rs

@@ -77,27 +77,25 @@ fn verify<Pair>(sig_data: Vec<u8>, message: Vec<u8>, uri: &str) -> error::Result
 {
 	let mut signature = Pair::Signature::default();
 	if sig_data.len() != signature.as_ref().len() {
-		return Err(error::Error::Other(format!(
-			"signature has an invalid length. read {} bytes, expected {} bytes",
-			sig_data.len(),
-			signature.as_ref().len(),
-		)));
+		return Err(
+			error::Error::SignatureInvalidLength {
+				read: sig_data.len(),
+				expected: signature.as_ref().len(),
+			}
+		);
 	}
 	signature.as_mut().copy_from_slice(&sig_data);
 
 	let pubkey = if let Ok(pubkey_vec) = hex::decode(uri) {
 		Pair::Public::from_slice(pubkey_vec.as_slice())
 	} else {
-		Pair::Public::from_string(uri)
-			.map_err(|_| {
-				error::Error::Other(format!("Invalid URI; expecting either a secret URI or a public URI."))
-			})?
+		Pair::Public::from_string(uri)?
 	};
 
 	if Pair::verify(&signature, &message, &pubkey) {
 		println!("Signature verifies correctly.");
 	} else {
-		return Err(error::Error::Other("Signature invalid.".into()))
+		return Err(error::Error::SignatureInvalid)
 	}
 
 	Ok(())