Fix custom emoji in notification

app/serializers/rest/notification_serializer.rb

@@ -6,7 +6,7 @@ class REST::NotificationSerializer < ActiveModel::Serializer
   belongs_to :from_account, key: :account, serializer: REST::AccountSerializer
   belongs_to :target_status, key: :status, if: :status_type?, serializer: REST::StatusSerializer
   belongs_to :report, if: :report_type?, serializer: REST::ReportSerializer
-  belongs_to :emoji_reaction, if: :emoji_reaction_type?, serializer: REST::EmojiReactionSerializer
+  belongs_to :emoji_reaction, if: :emoji_reaction_type?, serializer: REST::NotifyEmojiReactionSerializer
 
   def id
     object.id.to_s

app/serializers/rest/notify_emoji_reaction_serializer.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+class REST::NotifyEmojiReactionSerializer < ActiveModel::Serializer
+  include RoutingHelper
+  
+  attributes :name
+
+  attribute :count, if: :count?
+  attribute :url, if: :custom_emoji?
+  attribute :static_url, if: :custom_emoji?
+  attribute :domain, if: :custom_emoji?
+
+  def count?
+    object.respond_to?(:count)
+  end
+
+  def custom_emoji?
+    object.respond_to?(:custom_emoji) && object.custom_emoji.present?
+  end
+
+  def account_ids?
+    object.respond_to?(:account_ids)
+  end
+
+  def url
+    full_asset_url(object.custom_emoji.image.url)
+  end
+
+  def static_url
+    full_asset_url(object.custom_emoji.image.url(:static))
+  end
+
+  def domain
+    object.custom_emoji.domain
+  end
+end