Sinatra 2 issue with namespace

sinatra.log

bundle exec puma --port=9393 config.ru                        wip [2f7bc9b] (!) modified untracked
Puma starting in single mode...
* Version 3.11.3 (ruby 2.5.0-p0), codename: Love Song
* Min threads: 2, max threads: 10
* Environment: development
! Unable to load application: Mustermann::Error: #<Class:0x00007fb6e10c22a0>: Cannot translate Mustermann::AST::Node::WithLookAhead
Traceback (most recent call last):
  51: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/bin/ruby_executable_hooks:15:in `<main>'
  50: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/bin/ruby_executable_hooks:15:in `eval'
  49: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/bin/puma:23:in `<main>'
  48: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/bin/puma:23:in `load'
  47: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/puma-3.11.3/bin/puma:10:in `<top (required)>'
  46: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/puma-3.11.3/lib/puma/cli.rb:77:in `run'
  45: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/puma-3.11.3/lib/puma/launcher.rb:183:in `run'
  44: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/puma-3.11.3/lib/puma/single.rb:87:in `run'
  43: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/puma-3.11.3/lib/puma/runner.rb:138:in `load_and_bind'
  42: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/puma-3.11.3/lib/puma/configuration.rb:243:in `app'
  41: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/puma-3.11.3/lib/puma/configuration.rb:318:in `load_rackup'
  40: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/rack-2.0.4/lib/rack/builder.rb:40:in `parse_file'
  39: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/rack-2.0.4/lib/rack/builder.rb:49:in `new_from_string'
  38: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/rack-2.0.4/lib/rack/builder.rb:49:in `eval'
  37: from config.ru:in `<main>'
  36: from config.ru:in `new'
  35: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/rack-2.0.4/lib/rack/builder.rb:55:in `initialize'
  34: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/rack-2.0.4/lib/rack/builder.rb:55:in `instance_eval'
  33: from config.ru:1:in `block in <main>'
  32: from config.ru:1:in `require_relative'
  31: from /Users/antho/xxx/devops/concierge/concierge.rb:6:in `<top (required)>'
  30: from /Users/antho/xxx/devops/concierge/concierge.rb:6:in `each'
  29: from /Users/antho/xxx/devops/concierge/concierge.rb:6:in `block in <top (required)>'
  28: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/backports-3.11.1/lib/backports/std_lib.rb:9:in `require_with_backports'
  27: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/backports-3.11.1/lib/backports/std_lib.rb:9:in `require'
  26: from /Users/antho/xxx/devops/concierge/controllers/test.rb:1:in `<top (required)>'
  25: from /Users/antho/xxx/devops/concierge/controllers/test.rb:4:in `<class:TestController>'
  24: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:220:in `namespace'
  23: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:190:in `new'
  22: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:190:in `new'
  21: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:190:in `initialize'
  20: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:200:in `block in new'
  19: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:200:in `class_eval'
  18: from /Users/antho/xxx/devops/concierge/controllers/test.rb:5:in `block in <class:TestController>'
  17: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:229:in `block (2 levels) in prefixed'
  16: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:335:in `prefixed'
  15: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:322:in `compile'
  14: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/sinatra-contrib-2.0.1/lib/sinatra/namespace.rb:330:in `prefixed_path'
  13: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/concat.rb:17:in `+'
  12: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/sinatra.rb:83:in `native_concat'
  11: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/sinatra.rb:77:in `safe_string'
  10: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/ast/translator.rb:113:in `translate'
   9: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/sinatra/safe_renderer.rb:11:in `block (2 levels) in <class:Sinatra>'
   8: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/ast/translator.rb:41:in `t'
   7: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/ast/translator.rb:113:in `translate'
   6: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/sinatra/safe_renderer.rb:15:in `block (2 levels) in <class:Sinatra>'
   5: from /Users/antho/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/delegate.rb:83:in `method_missing'
   4: from /Users/antho/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/delegate.rb:83:in `map'
   3: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/sinatra/safe_renderer.rb:15:in `block (3 levels) in <class:Sinatra>'
   2: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/ast/translator.rb:41:in `t'
   1: from /Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/ast/translator.rb:113:in `translate'
/Users/antho/.rvm/gems/ruby-2.5.0@concierge/gems/mustermann-1.0.2/lib/mustermann/ast/translator.rb:106:in `decorator_for': #<Class:0x00007fb6e10c22a0>: Cannot translate Mustermann::AST::Node::WithLookAhead (Mustermann::Error)