Use before_action to handle missing status scenario in NotificationMailer

app/mailers/application_mailer.rb

@@ -9,6 +9,8 @@ class ApplicationMailer < ActionMailer::Base
 
   after_action :set_autoreply_headers!
 
+  rescue_from UncaughtThrowError, with: -> {}
+
   protected
 
   def locale_for_account(account, &block)

app/mailers/notification_mailer.rb

@@ -11,6 +11,7 @@ class NotificationMailer < ApplicationMailer
     after_action :thread_by_conversation!
   end
   before_action :set_account, only: [:follow, :favourite, :reblog, :follow_request]
+  before_action :verify_status_presence, only: %i(favourite mention reblog)
   after_action :set_list_headers!
 
   before_deliver :verify_functional_user
@@ -20,8 +21,6 @@ class NotificationMailer < ApplicationMailer
   layout 'mailer'
 
   def mention
-    return if @status.blank?
-
     locale_for_account(@me) do
       mail subject: default_i18n_subject(name: @status.account.acct)
     end
@@ -34,16 +33,12 @@ class NotificationMailer < ApplicationMailer
   end
 
   def favourite
-    return if @status.blank?
-
     locale_for_account(@me) do
       mail subject: default_i18n_subject(name: @account.acct)
     end
   end
 
   def reblog
-    return if @status.blank?
-
     locale_for_account(@me) do
       mail subject: default_i18n_subject(name: @account.acct)
     end
@@ -77,6 +72,10 @@ class NotificationMailer < ApplicationMailer
     throw(:abort) unless @user.functional?
   end
 
+  def verify_status_presence
+    throw(:abort) if @status.blank?
+  end
+
   def set_list_headers!
     headers(
       'List-ID' => "<#{@type}.#{@me.username}.#{Rails.configuration.x.local_domain}>",

spec/mailers/notification_mailer_spec.rb

@@ -14,6 +14,17 @@ RSpec.describe NotificationMailer do
     end
   end
 
+  shared_examples 'delivery without status' do
+    context 'when notification target_status is missing' do
+      before { allow(notification).to receive(:target_status).and_return(nil) }
+
+      it 'does not deliver mail' do
+        emails = capture_emails { mail.deliver_now }
+        expect(emails).to be_empty
+      end
+    end
+  end
+
   let(:receiver)       { Fabricate(:user, account_attributes: { username: 'alice' }) }
   let(:sender)         { Fabricate(:account, username: 'bob') }
   let(:foreign_status) { Fabricate(:status, account: sender, text: 'The body of the foreign status') }
@@ -37,6 +48,7 @@ RSpec.describe NotificationMailer do
     end
 
     include_examples 'delivery to non functional user'
+    include_examples 'delivery without status'
   end
 
   describe 'follow' do
@@ -75,6 +87,7 @@ RSpec.describe NotificationMailer do
     end
 
     include_examples 'delivery to non functional user'
+    include_examples 'delivery without status'
   end
 
   describe 'reblog' do
@@ -95,6 +108,7 @@ RSpec.describe NotificationMailer do
     end
 
     include_examples 'delivery to non functional user'
+    include_examples 'delivery without status'
   end
 
   describe 'follow_request' do