$ bundle exec ruby app.rb
/Users/james/.rvm/gems/ruby-3.1.2/gems/rack-2.2.4/lib/rack/handler.rb:45:in `pick': Couldn't find handler for: thin, puma, reel, HTTP, webrick. (LoadError)
	from /Users/james/.rvm/gems/ruby-3.1.2/gems/sinatra-2.2.2/lib/sinatra/base.rb:1503:in `run!'
	from /Users/james/.rvm/gems/ruby-3.1.2/gems/sinatra-2.2.2/lib/sinatra/main.rb:45:in `block in <module:Sinatra>'