Happy New Year!

I'm going to learn how to develop a OpenProject plugin.

I followed this tutorial to setup development environtment, when I try to run ./bin/rake db:migrate db:seed db:test:prepare, it show me this error:

    default: D, [2019-12-31T10:16:21.538846 #4285] DEBUG -- :   ↳ app/models/journal/aggregated_journal.rb:392:in `successor'
    default: D, [2019-12-31T10:16:21.562952 #4285] DEBUG -- :    (0.5ms)  SELECT "webhooks_webhooks"."id" FROM "webhooks_webhooks" INNER JOIN "webhooks_events" ON "webhooks_events"."webhooks_webhook_id" = "webhooks_webhooks"."id" WHERE "webhooks_webhooks"."enabled" = $1 AND "webhooks_webhooks"."enabled" = $2 AND "webhooks_events"."name" = $3 ORDER BY "webhooks_webhooks"."id" ASC  [["enabled", true], ["enabled", true], ["name", "work_package:created"]]
    default: D, [2019-12-31T10:16:21.563424 #4285] DEBUG -- :   ↳ modules/webhooks/lib/open_project/webhooks/event_resources/work_package.rb:26:in `handle_notification'
    default: D, [2019-12-31T10:16:21.564428 #4285] DEBUG -- :    (0.3ms)  ROLLBACK
    default: D, [2019-12-31T10:16:21.564648 #4285] DEBUG -- :   ↳ app/seeders/root_seeder.rb:57:in `do_seed!'
    default: rake aborted!
    default: ArgumentError: A copy of DemoData::References has been removed from the module tree but is still active!
    default: /home/vagrant/openproject/app/seeders/demo_data/references.rb:124:in `link_sprints'
    default: /home/vagrant/openproject/app/seeders/demo_data/references.rb:44:in `with_references'
    default: /home/vagrant/openproject/app/seeders/demo_data/work_package_seeder.rb:88:in `create_work_package'
    default: /home/vagrant/openproject/app/seeders/demo_data/work_package_seeder.rb:69:in `create_or_update_work_package'
    default: /home/vagrant/openproject/app/seeders/demo_data/work_package_seeder.rb:61:in `block in seed_demo_work_packages'
    default: /home/vagrant/openproject/app/seeders/demo_data/work_package_seeder.rb:59:in `each'
    default: /home/vagrant/openproject/app/seeders/demo_data/work_package_seeder.rb:59:in `seed_demo_work_packages'
    default: /home/vagrant/openproject/app/seeders/demo_data/work_package_seeder.rb:48:in `seed_data!'
    default: /home/vagrant/openproject/app/seeders/seeder.rb:33:in `seed!'
    default: /home/vagrant/openproject/app/seeders/demo_data/project_seeder.rb:66:in `block (2 levels) in seed_data!'
    default: /home/vagrant/openproject/app/seeders/demo_data/project_seeder.rb:64:in `each'
    default: /home/vagrant/openproject/app/seeders/demo_data/project_seeder.rb:64:in `block in seed_data!'
    default: /home/vagrant/openproject/app/seeders/demo_data/project_seeder.rb:37:in `each'
    default: /home/vagrant/openproject/app/seeders/demo_data/project_seeder.rb:37:in `seed_data!'
    default: /home/vagrant/openproject/app/seeders/seeder.rb:33:in `seed!'
    default: /home/vagrant/openproject/app/seeders/composite_seeder.rb:33:in `block (2 levels) in seed_data!'
    default: /home/vagrant/openproject/app/seeders/composite_seeder.rb:31:in `each'
    default: /home/vagrant/openproject/app/seeders/composite_seeder.rb:31:in `block in seed_data!'
    default: /home/vagrant/openproject/app/seeders/composite_seeder.rb:30:in `seed_data!'
    default: /home/vagrant/openproject/app/seeders/seeder.rb:33:in `seed!'
    default: /home/vagrant/openproject/app/seeders/root_seeder.rb:65:in `block in do_seed!'
    default: /home/vagrant/openproject/app/seeders/root_seeder.rb:57:in `do_seed!'
    default: /home/vagrant/openproject/app/seeders/root_seeder.rb:53:in `seed_data!'
    default: /home/vagrant/openproject/app/seeders/seeder.rb:33:in `seed!'
    default: /home/vagrant/openproject/db/seeds.rb:30:in `<main>'
    default: -e:1:in `<main>'
    default: Tasks: TOP => db:seed
    default: (See full trace by running task with --trace)

My development environment is CentOS7 + PostgreSQL10 in Vagrant. I uploaded my Vagrantfile as attachment. Please help.