Fix web server staying alive if Cucumber crashes
Fix web server staying alive if Cucumber crashes

`AfterAll` only runs if Cucumber doesn't crash, so this has to be an `at_exit`
bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js,bugsnag/bugsnag-js