example app: failure to kill new external service

[searls]

At the end of the example test run I'm seeing this:

/Users/justin/code/testdouble/cypress-rails/example/an_app/lib/external_service.rb:12:in `kill': No such process (Errno::ESRCH)
	from /Users/justin/code/testdouble/cypress-rails/example/an_app/lib/external_service.rb:12:in `block in stop_service'
	from /Users/justin/code/testdouble/cypress-rails/example/an_app/lib/external_service.rb:11:in `each'
	from /Users/justin/code/testdouble/cypress-rails/example/an_app/lib/external_service.rb:11:in `stop_service'
	from /Users/justin/code/testdouble/cypress-rails/example/an_app/config/initializers/cypress_rails_initializer.rb:38:in `block in <main>'
	from /Users/justin/code/testdouble/cypress-rails/lib/cypress-rails/initializer_hooks.rb:38:in `block in run'
	from /Users/justin/code/testdouble/cypress-rails/lib/cypress-rails/initializer_hooks.rb:37:in `each'
	from /Users/justin/code/testdouble/cypress-rails/lib/cypress-rails/initializer_hooks.rb:37:in `run'
	from /Users/justin/code/testdouble/cypress-rails/lib/cypress-rails/launches_cypress.rb:58:in `run_exit_hooks_if_necessary!'
	from /Users/justin/code/testdouble/cypress-rails/lib/cypress-rails/launches_cypress.rb:43:in `block in set_exit_hooks!'

Could you look at this @dflynn15?