fix(push_subscription): Guard against malformed favourite notification (#4271)

app/models/web/push_subscription.rb

@@ -26,8 +26,6 @@ class Web::PushSubscription < ApplicationRecord
   before_create :send_welcome_notification
 
   def push(notification)
-    return unless pushable? notification
-
     name = display_name notification.from_account
     title = title_str(name, notification)
     body = body_str notification
@@ -69,6 +67,10 @@ class Web::PushSubscription < ApplicationRecord
     )
   end
 
+  def pushable?(notification)
+    data && data.key?('alerts') && data['alerts'][notification.type.to_s]
+  end
+
   def as_payload
     payload = {
       id: id,
@@ -148,10 +150,6 @@ class Web::PushSubscription < ApplicationRecord
     rtl?(body) ? 'rtl' : 'ltr'
   end
 
-  def pushable?(notification)
-    data && data.key?('alerts') && data['alerts'][notification.type.to_s]
-  end
-
   def send_welcome_notification
     Webpush.payload_send(
       message: JSON.generate(

app/services/notify_service.rb

@@ -65,7 +65,12 @@ class NotifyService < BaseService
   end
 
   def send_push_notifications
-    sessions_with_subscriptions_ids = @recipient.user.session_activations.where.not(web_push_subscription: nil).pluck(:id)
+    # HACK: Can be caused by quickly unfavouriting a status, since creating
+    # a favourite and creating a notification are not wrapped in a transaction.
+    return if @notification.activity.nil?
+
+    sessions_with_subscriptions = @recipient.user.session_activations.where.not(web_push_subscription: nil)
+    sessions_with_subscriptions_ids = sessions_with_subscriptions.select { |session| session.web_push_subscription.pushable? @notification }.map(&:id)
 
     WebPushNotificationWorker.push_bulk(sessions_with_subscriptions_ids) do |session_activation_id|
       [session_activation_id, @notification.id]