From 7e785ed1012b828c834bbe1d1e13aec63fac2741 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Fri, 23 May 2025 23:52:30 +0200
Subject: [PATCH] state: fix undefined membership when handling MODE

Happens when the server sends a MODE message which refers to a user
who left the channel.
---
 state.js | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/state.js b/state.js
index 52ed1df..b09b913 100644
--- a/state.js
+++ b/state.js
@@ -670,12 +670,16 @@ export const State = {
 				let members = new irc.CaseMapMap(buf.members);
 
 				irc.forEachChannelModeUpdate(msg, client.isupport, (mode, add, arg) => {
-					if (prefixByMode.has(mode)) {
-						let nick = arg;
-						let membership = members.get(nick);
-						let letter = prefixByMode.get(mode);
-						members.set(nick, updateMembership(membership, letter, add, client));
+					if (!prefixByMode.has(mode)) {
+						return;
 					}
+					let nick = arg;
+					let membership = members.get(nick);
+					if (membership === undefined) {
+						return;
+					}
+					let letter = prefixByMode.get(mode);
+					members.set(nick, updateMembership(membership, letter, add, client));
 				});
 
 				return { members };