fix(ecstore): avoid warm tier init panics (#2144)

crates/ecstore/src/tier/warm_backend_rustfs.rs

@@ -72,12 +72,10 @@ impl WarmBackendRustFS {
         };
         let scheme = u.scheme();
         let default_port = if scheme == "https" { 443 } else { 80 };
-        let client = TransitionClient::new(
-            &format!("{}:{}", u.host_str().expect("err"), u.port().unwrap_or(default_port)),
-            opts,
-            "rustfs",
-        )
-        .await?;
+        let host = u
+            .host_str()
+            .ok_or_else(|| std::io::Error::other("endpoint URL must include a host"))?;
+        let client = TransitionClient::new(&format!("{host}:{}", u.port().unwrap_or(default_port)), opts, "rustfs").await?;
 
         let client = Arc::new(client);
         let core = TransitionCore(Arc::clone(&client));
@@ -158,3 +156,35 @@ fn optimal_part_size(object_size: i64) -> Result<i64, std::io::Error> {
     }
     Ok(part_size)
 }
+
+#[cfg(test)]
+mod tests {
+    use futures::FutureExt;
+    use std::panic::AssertUnwindSafe;
+
+    use super::*;
+
+    fn rustfs_tier(endpoint: &str) -> TierRustFS {
+        TierRustFS {
+            endpoint: endpoint.to_string(),
+            access_key: "access".to_string(),
+            secret_key: "secret".to_string(),
+            bucket: "bucket".to_string(),
+            ..Default::default()
+        }
+    }
+
+    #[tokio::test]
+    async fn new_returns_error_when_endpoint_has_no_host() {
+        let conf = rustfs_tier("rustfs://");
+
+        let outcome = AssertUnwindSafe(WarmBackendRustFS::new(&conf, "tier")).catch_unwind().await;
+
+        let result = outcome.expect("initialization should return an error instead of panicking");
+        let err = match result {
+            Ok(_) => panic!("endpoint without host must be rejected"),
+            Err(err) => err,
+        };
+        assert!(err.to_string().contains("host"), "expected host validation error, got: {err}");
+    }
+}