FIX: Don't raise error in update username job if user has been deleted.

app/jobs/regular/update_username.rb

@@ -7,6 +7,9 @@ module Jobs
 
     def execute(args)
       @user_id = args[:user_id]
+      user = User.find_by(id: @user_id)
+      return unless user
+
       @old_username = args[:old_username].unicode_normalize
       @new_username = args[:new_username].unicode_normalize
       @avatar_img = PrettyText.avatar_img(args[:avatar_template], "tiny")
@@ -36,7 +39,7 @@ module Jobs
       update_post_custom_fields
 
       DiscourseEvent.trigger(:username_changed, @old_username, @new_username)
-      DiscourseEvent.trigger(:user_updated, User.find_by(id: @user_id))
+      DiscourseEvent.trigger(:user_updated, user)
     end
 
     def update_posts

spec/jobs/update_username_spec.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Jobs::UpdateUsername do
+  fab!(:user) { Fabricate(:user) }
+
+  it 'does not do anything if user_id is invalid' do
+    events = DiscourseEvent.track_events do
+      described_class.new.execute(
+        user_id: -999,
+        old_username: user.username,
+        new_username: 'somenewusername',
+        avatar_template: user.avatar_template
+      )
+    end
+
+    expect(events).to eq([])
+  end
+end