From af2ac175e36a6a44bd41f725e89f711a0ca998a4 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Mon, 6 May 2024 02:30:00 -0400
Subject: [PATCH] fix deadlock on channel state mutex

---
 irc/getters.go | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/irc/getters.go b/irc/getters.go
index baf86cc6..984d3b6c 100644
--- a/irc/getters.go
+++ b/irc/getters.go
@@ -616,9 +616,11 @@ func (channel *Channel) Founder() string {
 
 func (channel *Channel) HighestUserMode(client *Client) (result modes.Mode) {
 	channel.stateMutex.RLock()
-	clientModes := channel.members[client].modes
-	channel.stateMutex.RUnlock()
-	return clientModes.HighestChannelUserMode()
+	defer channel.stateMutex.RUnlock()
+	if clientData, ok := channel.members[client]; ok {
+		return clientData.modes.HighestChannelUserMode()
+	}
+	return
 }
 
 func (channel *Channel) Settings() (result ChannelSettings) {