Add missing null check for inbound read receipts

node/src/client.js

@@ -155,10 +155,19 @@ class UserClient {
 		})
 
 		this.#talkClient.on("chat_read", (chat, channel, reader) => {
-			this.log(`Chat ${chat.logId} read in channel ${channel.channelId} by ${reader.userId}`)
+			let senderId
+			if (reader) {
+				senderId = reader.userId
+			} else if (channel.info.type == "MemoChat") {
+				senderId = channel.clientUser.userId
+			} else {
+				this.error(`Chat ${chat.logId} read in channel ${channel.channelId} by unknown reader (channel type: ${channel.info.type || "none"})`)
+				return
+			}
+			this.log(`Chat ${chat.logId} read in channel ${channel.channelId} by ${senderId}`)
 			this.write("chat_read", {
 				chatId: chat.logId,
-				senderId: reader.userId,
+				senderId: senderId,
 				channelId: channel.channelId,
 				channelType: channel.info.type,
 			})