Native Mercurial migration: crash on Note position
Seen while attempting to migrate heptapod/website>:
bundle exec rake heptapod:experimental:hg_migrate_native\[11,true\] RAILS_ENV=production
rake aborted!
ActiveRecord::RecordInvalid: Validation failed: Position must be a valid json schema
vendor/bundle/ruby/2.7/gems/activerecord-6.1.4.1/lib/active_record/validations.rb:80:in `raise_validation_error'
(...)
lib/heptapod/native_mercurial/migrator.rb:39:in `timeless_save'
lib/heptapod/native_mercurial/migrator.rb:199:in `save_note_if_changed'
(the rest of the backtrace does not provide more information