Changed initial connections error to return the last error

redis/src/cluster_async/mod.rs

@@ -534,15 +534,18 @@ where
     ) -> RedisResult<ConnectionMap<C>> {
         let initial_nodes: Vec<(String, Option<SocketAddr>)> =
             Self::try_to_expand_initial_nodes(initial_nodes).await;
+        let err = Arc::new(Mutex::new("".to_string()));
         let connections = stream::iter(initial_nodes.iter().cloned())
             .map(|node| {
+                let cloned_err = err.clone();
                 let params = params.clone();
                 async move {
                     let result = connect_and_check(&node.0, params, node.1).await;
                     match result {
                         Ok(conn) => Some((node.0, async { conn }.boxed().shared())),
                         Err(e) => {
                             trace!("Failed to connect to initial node: {:?}", e);
+                            *cloned_err.clone().lock().unwrap() = e.to_string();
                             None
                         }
                     }
@@ -558,9 +561,12 @@ where
             )
             .await;
         if connections.is_empty() {
+            let err_guard = err.lock().unwrap();
+
             return Err(RedisError::from((
                 ErrorKind::IoError,
                 "Failed to create initial connections",
+                err_guard.clone(),
             )));
         }
         Ok(connections)