Avoid panic if no rpc peers exist

core/src/replicator.rs

@@ -549,10 +549,13 @@ impl Replicator {
         previous_blockhash: &Hash,
     ) -> result::Result<(Hash, u64), Error> {
         for _ in 0..10 {
-            let rpc_client = {
+            let rpc_peers = {
                 let cluster_info = cluster_info.read().unwrap();
-                let rpc_peers = cluster_info.rpc_peers();
+                cluster_info.rpc_peers()
+            };
             debug!("rpc peers: {:?}", rpc_peers);
+            if !rpc_peers.is_empty() {
+                let rpc_client = {
                     let node_index = thread_rng().gen_range(0, rpc_peers.len());
                     RpcClient::new_socket(rpc_peers[node_index].rpc)
                 };
@@ -592,6 +595,7 @@ impl Replicator {
                         return Ok((storage_blockhash, storage_slot));
                     }
                 }
+            }
             info!("waiting for segment...");
             sleep(Duration::from_secs(5));
         }