La parte pertinente del log è
undefined method `+' for nil
/var/www/discourse/db/migrate/20241025045928_add_invites_link_to_sidebar.rb:44:in `up'
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/activerecord-7.1.4.2/lib/active_record/migration.rb:989:in `public_send'
Quindi sembra correlato a FEATURE: Add invite link to the sidebar (#29448) · discourse/discourse@19672fa · GitHub (cc @osama)