FIX: 500 error when reviewable has a missing message (#397)

app/models/reviewable_ai_chat_message.rb

@@ -34,7 +34,8 @@ class ReviewableAiChatMessage < Reviewable
 
   def build_actions(actions, guardian, args)
     return unless pending?
-    return if chat_message.blank?
+
+    return build_action(actions, :ignore, icon: "external-link-alt") if chat_message.blank?
 
     agree =
       actions.add_bundle("#{id}-agree", icon: "thumbs-up", label: "reviewables.actions.agree.title")

app/serializers/reviewable_ai_chat_message_serializer.rb

@@ -10,7 +10,7 @@ class ReviewableAiChatMessageSerializer < ReviewableSerializer
   has_one :chat_channel, serializer: AiChatChannelSerializer, root: false, embed: :objects
 
   def chat_channel
-    object.chat_message.chat_channel
+    object.chat_message&.chat_channel
   end
 
   def target_id

assets/javascripts/discourse/components/reviewable-ai-chat-message.hbs

@@ -1,4 +1,5 @@
-<div class="flagged-post-header">
+{{#if this.chatChannel}}
+  <div class="flagged-post-header">
     <LinkTo
       @route="chat.channel.near-message"
       @models={{array
@@ -9,7 +10,8 @@
     >
       <ChatChannelTitle @channel={{this.chatChannel}} />
     </LinkTo>
-</div>
+  </div>
+{{/if}}
 
 <div class="post-contents-wrapper">
   <ReviewableCreatedBy @user={{@reviewable.target_created_by}} @tagName="" />

assets/javascripts/discourse/components/reviewable-ai-chat-message.js

@@ -3,6 +3,9 @@ import ChatChannel from "discourse/plugins/chat/discourse/models/chat-channel";
 
 export default class ReviewableAiChatMessage extends Component {
   get chatChannel() {
+    if (!this.args.reviewable.chat_channel) {
+      return;
+    }
     return ChatChannel.create(this.args.reviewable.chat_channel);
   }
 }

spec/system/toxicity/reviewable_ai_chat_message_spec.rb

@@ -23,4 +23,20 @@ RSpec.describe "Toxicity-flagged chat messages", type: :system, js: true do
 
     expect(page).to have_selector(".reviewable-ai-chat-message .reviewable-actions")
   end
+
+  context "when the message is hard deleted" do
+    before { chat_message.destroy! }
+
+    it "does not throw an error" do
+      visit("/review")
+
+      expect(page).to have_selector(".reviewable-ai-chat-message .reviewable-actions")
+    end
+
+    it "adds the option to ignore the flag" do
+      visit("/review")
+
+      expect(page).to have_selector(".reviewable-actions .chat-message-ignore")
+    end
+  end
 end