fix: Handle the case where message has no attachments (#9902)

Fix the broken message sending due to the errors in attachment update PR
https://github.com/chatwoot/chatwoot/pull/9784

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/javascript/dashboard/store/modules/conversations/index.js

@@ -146,7 +146,10 @@ export const mutations = {
 
   [types.ADD_CONVERSATION_ATTACHMENTS](_state, message) {
     // early return if the message has not been sent, or has no attachments
-    if (message.status !== MESSAGE_STATUS.SENT || !message.attachments.length) {
+    if (
+      message.status !== MESSAGE_STATUS.SENT ||
+      !message.attachments?.length
+    ) {
       return;
     }