From e49a3e131361da0d3c769c781eab29ec07f76765 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Wed, 16 Sep 2020 17:19:45 +1000
Subject: [PATCH] Return result in client builder

---
 beacon_node/client/src/builder.rs | 50 +++++++++++++++----------------
 beacon_node/src/lib.rs            | 19 ++++++------
 2 files changed, 34 insertions(+), 35 deletions(-)

diff --git a/beacon_node/client/src/builder.rs b/beacon_node/client/src/builder.rs
index 1fccad6129a..d530605adb2 100644
--- a/beacon_node/client/src/builder.rs
+++ b/beacon_node/client/src/builder.rs
@@ -335,19 +335,25 @@ where
     /// If type inference errors are being raised, see the comment on the definition of `Self`.
     pub fn build(
         self,
-    ) -> Client<
-        Witness<
-            TStoreMigrator,
-            TSlotClock,
-            TEth1Backend,
-            TEthSpec,
-            TEventHandler,
-            THotStore,
-            TColdStore,
+    ) -> Result<
+        Client<
+            Witness<
+                TStoreMigrator,
+                TSlotClock,
+                TEth1Backend,
+                TEthSpec,
+                TEventHandler,
+                THotStore,
+                TColdStore,
+            >,
         >,
+        String,
     > {
-        // TODO: fix unwrap.
-        let log = self.runtime_context.as_ref().unwrap().log().clone();
+        let runtime_context = self
+            .runtime_context
+            .as_ref()
+            .ok_or_else(|| "build requires a runtime context".to_string())?;
+        let log = runtime_context.log().clone();
 
         let http_api_listen_addr = if self.http_api_config.enabled {
             let ctx = Arc::new(http_api::Context {
@@ -358,16 +364,13 @@ where
                 log: log.clone(),
             });
 
-            // TODO
-            let exit = self.runtime_context.as_ref().unwrap().executor.exit();
+            let exit = runtime_context.executor.exit();
 
             let (listen_addr, server) = http_api::serve(ctx, exit)
-                .map_err(|e| format!("Unable to start HTTP API server: {:?}", e))
-                .unwrap(); // TODO
+                .map_err(|e| format!("Unable to start HTTP API server: {:?}", e))?;
 
-            self.runtime_context
+            runtime_context
                 .clone()
-                .unwrap()
                 .executor
                 .spawn_without_exit(async move { server.await }, "http-api");
 
@@ -386,15 +389,12 @@ where
                 log: log.clone(),
             });
 
-            // TODO
-            let exit = self.runtime_context.as_ref().unwrap().executor.exit();
+            let exit = runtime_context.executor.exit();
 
             let (listen_addr, server) = http_metrics::serve(ctx, exit)
-                .map_err(|e| format!("Unable to start HTTP API server: {:?}", e))
-                .unwrap(); // TODO
+                .map_err(|e| format!("Unable to start HTTP API server: {:?}", e))?;
 
-            self.runtime_context
-                .unwrap()
+            runtime_context
                 .executor
                 .spawn_without_exit(async move { server.await }, "http-api");
 
@@ -404,13 +404,13 @@ where
             None
         };
 
-        Client {
+        Ok(Client {
             beacon_chain: self.beacon_chain,
             network_globals: self.network_globals,
             http_api_listen_addr,
             http_metrics_listen_addr,
             websocket_listen_addr: self.websocket_listen_addr,
-        }
+        })
     }
 }
 
diff --git a/beacon_node/src/lib.rs b/beacon_node/src/lib.rs
index b00ffd8de79..feff1e3206f 100644
--- a/beacon_node/src/lib.rs
+++ b/beacon_node/src/lib.rs
@@ -124,16 +124,15 @@ impl<E: EthSpec> ProductionBeaconNode<E> {
         // Inject the executor into the discv5 network config.
         client_config.network.discv5_config.executor = Some(Box::new(executor));
 
-        Ok(Self(
-            builder
-                .build_beacon_chain()?
-                .network(&client_config.network)
-                .await?
-                .notifier()?
-                .http_api_config(client_config.http_api.clone())
-                .http_metrics_config(client_config.http_metrics.clone())
-                .build(),
-        ))
+        builder
+            .build_beacon_chain()?
+            .network(&client_config.network)
+            .await?
+            .notifier()?
+            .http_api_config(client_config.http_api.clone())
+            .http_metrics_config(client_config.http_metrics.clone())
+            .build()
+            .map(Self)
     }
 
     pub fn into_inner(self) -> ProductionClient<E> {