Too few arguments passed to Drupal\file_example\FileExampleSubmitHandlerHelper::__construct(): 7 passed and exactly 8 expected

Problem/Motivation

Trying to access /examples/file_example throws the following exception.

ArgumentCountError: Too few arguments to function Drupal\file_example\FileExampleSubmitHandlerHelper::__construct(), 7 passed in /var/www/html/web/core/lib/Drupal/Component/DependencyInjection/Container.php on line 259 and exactly 8 expected in Drupal\file_example\FileExampleSubmitHandlerHelper->__construct() (line 45 of modules/contrib/examples/modules/file_example/src/FileExampleSubmitHandlerHelper.php).

Steps to reproduce

• Install the File Example module
• On the toolbar, click on Examples, then on File Example

Proposed resolution

Add @module_handler to the list of the arguments passed to the file_example.submit_handler_helper service (as last argument).
In this way, the number of arguments passed to FileExampleSubmitHandlerHelper::__construct() matches the number of parameters that constructor defines.