module Roda::RodaPlugins::Base::ClassMethods

def freeze

it would cause some plugins to break.
Note that freezing the class prevents you from subclassing it, mostly because

be raised if you try to modify the internal state after calling this.
internal state at runtime anyway, but this makes sure an exception will
It's optional to call this method, as nothing should be modifying the
Freeze the internal state of the class, to avoid thread safety issues at runtime. 
def freeze
  return self if frozen?
  unless opts[:subclassed]
    # If the _roda_run_main_route instance method has not been overridden,
    # make it an alias to _roda_main_route for performance
    if instance_method(:_roda_run_main_route).owner == InstanceMethods
      class_eval("alias _roda_run_main_route _roda_main_route")
    end
    self::RodaResponse.class_eval do
      if instance_method(:set_default_headers).owner == ResponseMethods &&
         instance_method(:default_headers).owner == ResponseMethods
        private
        alias set_default_headers set_default_headers
        def set_default_headers
          @headers['Content-Type'] ||= 'text/html'
        end
      end
    end
    if @middleware.empty? && use_new_dispatch_api?
      plugin :direct_call
    end
  end
  build_rack_app
  @opts.freeze
  @middleware.freeze
  super
end