message: fix(elements): strict null checks
  PR Close
diff: @@ -3,11 +3,11 @@ import {AppModuleNgFactory} from './app.ngfactory';
  platformBrowser().bootstrapModuleFactory(AppModuleNgFactory, {ngZone: 'noop'});
  -const helloWorldEl = document.querySelector('hello-world-el');
  +const helloWorld = document.querySelector('hello-world-el');
  const input = document.querySelector('input[type=text]');
  -if(input){
  +if(input && helloWorld){
  input.addEventListener('input', e => {
  const newText = (e.target as any).value;
  - helloWorldEl.setAttribute('name', newText);
  + helloWorld.setAttribute('name', newText);
  });
  }
  