FIX: Don't error when navigating from AI Bot topic to regular (#1366)

We were getting an error in this logic causing Ember to fail to render the non-bot-topic that we navigate to.

I believe this is because the getter of participants is re-calculating (due to this.header.topicInfo being updated) before the args to this connector changes. Adding some safe navigation here fixes the issue.

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;
   }

spec/system/ai_bot/homepage_spec.rb

@@ -109,6 +109,33 @@
     before { SiteSetting.glimmer_post_stream_mode = value }
 
     context "when glimmer_post_stream_mode=#{value}" do
+      context "when mobile", mobile: true do
+        it "allows navigating from AI conversation to regular topic, and loads new post stream" do
+          regular_topic = Fabricate(:topic)
+          regular_post = Fabricate(:post, topic: regular_topic)
+
+          post_url = Topic.relative_url(regular_topic.id, regular_topic.slug)
+          post_with_link =
+            Fabricate(
+              :post,
+              topic: pm,
+              user: user,
+              post_number: 4,
+              raw: "This is a second reply by the user [link](#{post_url})",
+            )
+
+          topic_page.visit_topic(pm)
+          page.find(
+            "article[data-post-id='#{post_with_link.id}'] .cooked a[href='#{post_url}']",
+          ).click
+
+          try_until_success do
+            expect(topic_page.current_topic).to eq(regular_topic)
+            expect(page).to have_css("article[data-post-id='#{regular_post.id}']")
+          end
+        end
+      end
+
       context "when `ai_bot_enable_dedicated_ux` is enabled" do
         it "allows uploading files to a new conversation" do
           ai_pm_homepage.visit