TYPO3 How can I get all validation errors before being output to view

问题

In TYPO3 own extension validation of form inputs is done before control is handed over to the controller action. How can I get to work on the validation errors before being handed over to view?

来源：https://stackoverflow.com/questions/61747161/typo3-how-can-i-get-all-validation-errors-before-being-output-to-view