FIX: Some solved topics have no answers

lib/discourse_solved/topic_view_serializer_extension.rb

@@ -6,7 +6,8 @@ module DiscourseSolved::TopicViewSerializerExtension
   prepended { attributes :accepted_answer }
 
   def include_accepted_answer?
-    SiteSetting.solved_enabled? && object.topic.solved.present?
+    SiteSetting.solved_enabled? && object.topic.solved.present? &&
+      object.topic.solved.answer_post.present?
   end
 
   def accepted_answer

spec/serializers/topic_view_serializer_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+describe TopicViewSerializer do
+  fab!(:topic)
+  fab!(:post1) { Fabricate(:post, topic:) }
+  fab!(:post2) { Fabricate(:post, topic:) }
+  fab!(:user)
+
+  before { SiteSetting.solved_enabled = true }
+
+  describe "#accepted_answer" do
+    it "returns the accepted answer post when the topic has an accepted answer" do
+      Fabricate(:solved_topic, topic: topic, answer_post: post2)
+      serializer = TopicViewSerializer.new(TopicView.new(topic), scope: Guardian.new(user))
+      serialized = serializer.as_json
+      expect(serialized[:topic_view][:accepted_answer][:post_number]).to eq(post2.post_number)
+    end
+
+    it "returns nil when the topic does not have an accepted answer" do
+      unsolved_topic = Fabricate(:topic)
+      serializer = TopicViewSerializer.new(TopicView.new(unsolved_topic), scope: Guardian.new(user))
+      serialized = serializer.as_json
+      expect(serialized[:accepted_answer]).to be_nil
+    end
+
+    it "returns nil when the accepted answer post does not exist" do
+      weird_topic = Fabricate(:solved_topic)
+      weird_topic.update!(answer_post_id: 19_238_319)
+      serializer =
+        TopicViewSerializer.new(TopicView.new(weird_topic.topic), scope: Guardian.new(user))
+      serialized = serializer.as_json
+      expect(serialized[:accepted_answer]).to be_nil
+    end
+  end
+end