The DIV generated by the top level component error handler should have a class

In order easily style the top level component error handler back stop it should have a class (like ''hyperstack-top-level-error-boundry' that you can set the CSS for.

I.e. make the text smaller, and give it a white background, etc.

Here is a patch:

module Hyperstack
  class Hotloader
    module AddErrorBoundry
      # don't attempt the alias unless the method is defined.
      # for example if HotLoader is not included in the stack
      alias original_display_error display_error if method_defined? :display_error
      def display_error(*args)
        DIV(class: 'hyperstack-top-level-error-boundry') { original_display_error(*args) }
      end
    end
  end
end

Be sure to have the method_defined? guard defined, otherwise you may discover in test or worse in production things won't boot