From 9da71e1b59334cb146b218454c034f363b6dc168 Mon Sep 17 00:00:00 2001
From: Debby Mendez <118911638+debbyglance@users.noreply.github.com>
Date: Mon, 28 Oct 2024 09:56:13 -0400
Subject: [PATCH] Fix issue #624

A cancelled future in the flush_queue can cause the flusher task to fail with InvalidStateError, attempting to set the result on a "done" future.
---
 nats/aio/client.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/nats/aio/client.py b/nats/aio/client.py
index 81e65f50..e5ca2834 100644
--- a/nats/aio/client.py
+++ b/nats/aio/client.py
@@ -2084,7 +2084,9 @@ async def _flusher(self) -> None:
                 # RuntimeError in case the event loop is closed
                 break
             finally:
-                future.set_result(None)
+                # future might have been cancelled.  See issue #624
+                if not future.done():
+                    future.set_result(None)
 
     async def _ping_interval(self) -> None:
         while True: