If you get the following error when starting with your react native app
Application AwesomeProject has not been registered. This is either due to a require() error during initialization or failure to call AppRegistry.registerComponent.
You probably are following the react native tutorial here. When you past the code from the hello world example here your registered component name is not matching since you first one was AwesomeProject and the new one is HelloWorld. Just change
AppRegistry.registerComponent( 'HelloWorldApp', () => HelloWorldApp );