AO3-6773 fix url param pluralisation in invite_request_declined maile…

…r preview update

test/mailers/previews/user_mailer_preview.rb

@@ -42,7 +42,7 @@ def claim_notification
 
   def invite_request_declined
     user = create(:user, :for_mailer_preview)
-    total = params[:total].to_i || 1
+    total = params[:total] ? params[:total].to_i : 1
     reason = "test reason"
     UserMailer.invite_request_declined(user.id, total, reason)
   end