In chapter 4 (around pages 97-99) we are shown how to create a new output formatter which will render the page in Yaml syntax, but it results in:
This webpage is not available (Chrome, with a console error of 'net::ERR_INVALID_RESPONSE')
File not found (Firefox)
In chapter 4 (around pages 95-96) we are shown a throwaway snippet as an example of outputting a view in JSON format which results in a fatal error:
PHP Fatal Error – yii\base\ErrorException Class 'app\controllers\Response' not found