NotImplementedError when using new navigation with an ultimate trial

Summary

There's a NotImplementedError that causes a 500 error when visiting a group that just enabled an ultimate trial. I had the issue with https://gitlab.com/repro_1941803 but it's a private group. I tested that I still had the error if I switched it to public though. Here's the stack trace:

      "exception.backtrace": [
        "lib/sidebars/concerns/container_with_html_options.rb:57:in `title'",
        "lib/sidebars/menu.rb:143:in `serialize_as_menu_item_args'",
        "lib/sidebars/concerns/super_sidebar_panel.rb:25:in `block in transform_old_menus'",
        "lib/sidebars/concerns/super_sidebar_panel.rb:20:in `each'",
        "lib/sidebars/concerns/super_sidebar_panel.rb:20:in `transform_old_menus'",
        "lib/sidebars/groups/super_sidebar_panel.rb:31:in `configure_menus'",
        "lib/sidebars/panel.rb:16:in `initialize'",
        "app/helpers/sidebars_helper.rb:107:in `new'",
        "app/helpers/sidebars_helper.rb:107:in `super_sidebar_nav_panel'",
        "app/views/layouts/_page.html.haml:8",
        "app/views/layouts/application.html.haml:22",
        "app/views/layouts/group.html.haml:26",
        "app/controllers/application_controller.rb:142:in `render'",
        "app/controllers/groups_controller.rb:235:in `render_show_html'",
        "ee/app/controllers/ee/groups_controller.rb:39:in `render_show_html'",
        "app/controllers/groups_controller.rb:101:in `block (2 levels) in show'",
        "app/controllers/groups_controller.rb:96:in `show'",
        "ee/lib/gitlab/ip_address_state.rb:10:in `with'",
        "ee/app/controllers/ee/application_controller.rb:45:in `set_current_ip_address'",
        "app/controllers/application_controller.rb:524:in `set_current_admin'",
        "lib/gitlab/session.rb:11:in `with_session'",
        "app/controllers/application_controller.rb:515:in `set_session_storage'",
        "lib/gitlab/i18n.rb:107:in `with_locale'",
        "lib/gitlab/i18n.rb:113:in `with_user_locale'",
        "app/controllers/application_controller.rb:506:in `set_locale'",
        "app/controllers/application_controller.rb:499:in `set_current_context'",
        "ee/lib/omni_auth/strategies/group_saml.rb:41:in `other_phase'",
        "lib/gitlab/metrics/elasticsearch_rack_middleware.rb:16:in `call'",
        "lib/gitlab/middleware/memory_report.rb:13:in `call'",
        "lib/gitlab/middleware/speedscope.rb:13:in `call'",
        "lib/gitlab/database/load_balancing/rack_middleware.rb:23:in `call'",
        "lib/gitlab/middleware/rails_queue_duration.rb:33:in `call'",
        "lib/gitlab/metrics/rack_middleware.rb:16:in `block in call'",
        "lib/gitlab/metrics/web_transaction.rb:46:in `run'",
        "lib/gitlab/metrics/rack_middleware.rb:16:in `call'",
        "lib/gitlab/jira/middleware.rb:19:in `call'",
        "lib/gitlab/middleware/go.rb:20:in `call'",
        "lib/gitlab/etag_caching/middleware.rb:21:in `call'",
        "lib/gitlab/middleware/query_analyzer.rb:11:in `block in call'",
        "lib/gitlab/database/query_analyzer.rb:37:in `within'",
        "lib/gitlab/middleware/query_analyzer.rb:11:in `call'",
        "lib/gitlab/middleware/multipart.rb:173:in `call'",
        "lib/gitlab/middleware/read_only/controller.rb:50:in `call'",
        "lib/gitlab/middleware/read_only.rb:18:in `call'",
        "lib/gitlab/middleware/same_site_cookies.rb:27:in `call'",
        "lib/gitlab/middleware/basic_health_check.rb:25:in `call'",
        "lib/gitlab/middleware/handle_malformed_strings.rb:21:in `call'",
        "lib/gitlab/middleware/handle_ip_spoof_attack_error.rb:25:in `call'",
        "lib/gitlab/middleware/request_context.rb:21:in `call'",
        "lib/gitlab/middleware/webhook_recursion_detection.rb:15:in `call'",
        "config/initializers/fix_local_cache_middleware.rb:11:in `call'",
        "lib/gitlab/middleware/compressed_json.rb:37:in `call'",
        "lib/gitlab/middleware/rack_multipart_tempfile_factory.rb:19:in `call'",
        "lib/gitlab/middleware/sidekiq_web_static.rb:20:in `call'",
        "lib/gitlab/metrics/requests_rack_middleware.rb:79:in `call'",
        "lib/gitlab/middleware/release_env.rb:13:in `call'"
      ],

Correlation ID 01GYCP93NZD8VS23PZM162B6X2

Steps to reproduce

Create a group, start an ultimate trial, visit the group page (you will be redirected there anyway)

Example Project

https://gitlab.com/repro_1941803

What is the current bug behavior?

500 error when accessing the group with the new navigation is enabled

What is the expected correct behavior?

There shouldn't be an error

Relevant logs and/or screenshots

See above

Output of checks

This bug happens on GitLab.com /label reproduced on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes

Not a fix, but opting out of the new navigation is a workaround