FIX: Don't error when navigating from AI Bot topic to regular

Author: markvanlan

assets/javascripts/discourse/connectors/topic-map-participants-after/ai-conversation-invite.gjs

@@ -18,8 +18,8 @@ export default class AiConversationInvite extends Component {
 
   get participants() {
     const participants = [
-      ...this.header.topicInfo.details.allowed_users,
-      ...this.header.topicInfo.details.allowed_groups,
+      ...(this.header.topicInfo.details?.allowed_users ?? []),
+      ...(this.header.topicInfo.details?.allowed_groups ?? []),
     ];
     return participants;
   }