Fix undefined chat message signatures causing crash (#1413)

* Fix undefined chat message signatures causing crash

* Update src/client/chat.js

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update chat.js lint

---------

Co-authored-by: extremeheat <extreme@protonmail.ch>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: 3 people

src/client/chat.js

@@ -59,8 +59,14 @@ module.exports = function (client, options) {
 
       if (player.hasChainIntegrity) {
         const length = Buffer.byteLength(message, 'utf8')
-        const acknowledgements = previousMessages.length > 0 ? ['i32', previousMessages.length, 'buffer', Buffer.concat(...previousMessages.map(msg => msg.signature || client._signatureCache[msg.id]))] : ['i32', 0]
-
+        const validBuffers = previousMessages
+          .filter(msg => msg.signature || client._signatureCache[msg.id]) // Filter out invalid messages
+          .map(msg => msg.signature || client._signatureCache[msg.id])
+          .filter(buf => Buffer.isBuffer(buf))
+
+        const acknowledgements = validBuffers.length > 0
+          ? ['i32', validBuffers.length, 'buffer', Buffer.concat(validBuffers)]
+          : ['i32', 0]
         const signable = concat('i32', 1, 'UUID', uuid, 'UUID', player.sessionUuid, 'i32', index, 'i64', salt, 'i64', timestamp / 1000n, 'i32', length, 'pstring', message, ...acknowledgements)
 
         player.hasChainIntegrity = crypto.verify('RSA-SHA256', signable, player.publicKey, currentSignature)