Propagate Esplora client setup failures

Return Esplora client construction failures through build-time error handling instead of panicking so invalid headers or reqwest setup errors fail node construction cleanly.

Co-Authored-By: HAL 9000

Author: tnull

src/builder.rs

@@ -189,6 +189,8 @@ pub enum BuildError {
 	WalletSetupFailed,
 	/// We failed to setup the logger.
 	LoggerSetupFailed,
+	/// We failed to setup the configured chain source.
+	ChainSourceSetupFailed,
 	/// The given network does not match the node's previously configured network.
 	NetworkMismatch,
 	/// The role of the node in an asynchronous payments context is not compatible with the current configuration.
@@ -216,6 +218,7 @@ impl fmt::Display for BuildError {
 			Self::KVStoreSetupFailed => write!(f, "Failed to setup KVStore."),
 			Self::WalletSetupFailed => write!(f, "Failed to setup onchain wallet."),
 			Self::LoggerSetupFailed => write!(f, "Failed to setup the logger."),
+			Self::ChainSourceSetupFailed => write!(f, "Failed to setup the chain source."),
 			Self::InvalidNodeAlias => write!(f, "Given node alias is invalid."),
 			Self::NetworkMismatch => {
 				write!(f, "Given network does not match the node's previously configured network.")
@@ -1314,6 +1317,7 @@ fn build_with_store_internal(
 				Arc::clone(&logger),
 				Arc::clone(&node_metrics),
 			)
+			.map_err(|()| BuildError::ChainSourceSetupFailed)?
 		},
 		Some(ChainDataSourceConfig::Electrum { server_url, sync_config }) => {
 			let sync_config = sync_config.unwrap_or(ElectrumSyncConfig::default());
@@ -1383,6 +1387,7 @@ fn build_with_store_internal(
 				Arc::clone(&logger),
 				Arc::clone(&node_metrics),
 			)
+			.map_err(|()| BuildError::ChainSourceSetupFailed)?
 		},
 	};
 	let chain_source = Arc::new(chain_source);

src/chain/esplora.rs

@@ -45,7 +45,7 @@ impl EsploraChainSource {
 		server_url: String, headers: HashMap<String, String>, sync_config: EsploraSyncConfig,
 		fee_estimator: Arc<OnchainFeeEstimator>, kv_store: Arc<DynStore>, config: Arc<Config>,
 		logger: Arc<Logger>, node_metrics: Arc<RwLock<NodeMetrics>>,
-	) -> Self {
+	) -> Result<Self, ()> {
 		let mut client_builder = esplora_client::Builder::new(&server_url);
 		client_builder =
 			client_builder.timeout(sync_config.timeouts_config.per_request_timeout_secs as u64);
@@ -54,14 +54,15 @@ impl EsploraChainSource {
 			client_builder = client_builder.header(header_name, header_value);
 		}
 
-		let esplora_client =
-			client_builder.build_async().expect("esplora client build must succeed");
+		let esplora_client = client_builder.build_async().map_err(|e| {
+			log_error!(logger, "Failed to build Esplora client: {}", e);
+		})?;
 		let tx_sync =
 			Arc::new(EsploraSyncClient::from_client(esplora_client.clone(), Arc::clone(&logger)));
 
 		let onchain_wallet_sync_status = Mutex::new(WalletSyncStatus::Completed);
 		let lightning_wallet_sync_status = Mutex::new(WalletSyncStatus::Completed);
-		Self {
+		Ok(Self {
 			sync_config,
 			esplora_client,
 			onchain_wallet_sync_status,
@@ -72,7 +73,7 @@ impl EsploraChainSource {
 			config,
 			logger,
 			node_metrics,
-		}
+		})
 	}
 
 	pub(super) async fn sync_onchain_wallet(

src/chain/mod.rs

@@ -101,7 +101,7 @@ impl ChainSource {
 		fee_estimator: Arc<OnchainFeeEstimator>, tx_broadcaster: Arc<Broadcaster>,
 		kv_store: Arc<DynStore>, config: Arc<Config>, logger: Arc<Logger>,
 		node_metrics: Arc<RwLock<NodeMetrics>>,
-	) -> (Self, Option<BestBlock>) {
+	) -> Result<(Self, Option<BestBlock>), ()> {
 		let esplora_chain_source = EsploraChainSource::new(
 			server_url,
 			headers,
@@ -111,10 +111,10 @@ impl ChainSource {
 			config,
 			Arc::clone(&logger),
 			node_metrics,
-		);
+		)?;
 		let kind = ChainSourceKind::Esplora(esplora_chain_source);
 		let registered_txids = Mutex::new(Vec::new());
-		(Self { kind, registered_txids, tx_broadcaster, logger }, None)
+		Ok((Self { kind, registered_txids, tx_broadcaster, logger }, None))
 	}
 
 	pub(crate) fn new_electrum(