Upgrading from Satellite 6.9 to Satellite 6.10 fails with error "undefined method operatingsystems' for nil:NilClass"

Issue

• Upgrading from Satellite 6.9 to Satellite 6.10 fails with error undefined method operatingsystems' for nil:NilClass during the db:migrate step i.e. while applying the 20210115124508 TemplateKindRegistration migration:

  undefined method operatingsystems' for nil:NilClass /usr/share/foreman/db/migrate/20210115124508_template_kind_registration.rb:26:in block in up'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/relation/delegation.rb:87:in each' /opt/theforeman/tfm/root/usr/share /gems/gems/activerecord-6.0.3.7/lib/active_record/relation/delegation.rb:87:in each'
  /usr/share/foreman/db/migrate/20210115124508_template_kind_registration.rb:25:in up' /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7 /lib/active_record/migration.rb:831:in exec_migration'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/migration.rb:812:in block (2 levels) in migrate' /opt/rh/rh-ruby27/root/usr /share/ruby/benchmark.rb:293:in measure'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/migration.rb:811:in block in migrate' /opt/theforeman/tfm/root/usr/share  /gems/gems/activerecord-6.0.3.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:471:in with_connection'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/migration.rb:810:in migrate' /opt/theforeman/tfm/root/usr/share /gems/gems/activerecord-6.0.3.7/lib/active_record/migration.rb:1002:in migrate'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/migration.rb:1310:in block in execute_migration_in_transaction'   /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/migration.rb:1361:in block in ddl_transaction'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/connection_adapters/abstract/database_statements.rb:280:in block in transaction' /opt/theforeman/tfm/root/usr/share/gems/gems/activerecord-6.0.3.7/lib/active_record/connection_adapters/abstract/transaction.rb:280:in block in within_new_transaction'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activesupport-6.0.3.7/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in block (2 levels) in synchronize' /opt/theforeman/tfm/root/usr/share/gems/gems/activesupport-6.0.3.7/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in handle_interrupt'
  /opt/theforeman/tfm/root/usr/share/gems/gems/activesupport-6.0.3.7/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in block in synchronize' /opt/theforeman/tfm/root/usr/share/gems/gems/activesupport-6.0.3.7/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in handle_interrupt'