warnings when running `drush st` in the sut folder

[joachim-n]

I cloned this repo, did:

composer install
composer drupal:scaffold

Since I had no idea what the second command does, or indeed, how much the first command installs, I went into the sut folder and did:

drush st

just to get an idea of what there, if anything.

I got these two warnings:

 [warning] include(/Users/joachim/Sites/_sandbox/example-drush-extension/sut/ExampleCommands.php): failed to open stream: No such file or directory Application.php:361
 [warning] include(): Failed opening '/Users/joachim/Sites/_sandbox/example-drush-extension/sut/ExampleCommands.php' for inclusion (include_path='/Users/joachim/Sites/_sandbox/example-drush-extension/vendor/pear/pear_exception:/Users/joachim/Sites/_sandbox/example-drush-extension/vendor/pear/console_getopt:/Users/joachim/Sites/_sandbox/example-drush-extension/vendor/pear/pear-core-minimal/src:/Users/joachim/Sites/_sandbox/example-drush-extension/vendor/pear/archive_tar:.:/Applications/MAMP/bin/php/php7.2.10/lib/php') Application.php:361
 Drupal version : 8.7.2
 Site URI       : http://default
 PHP binary     : /Applications/MAMP/bin/php/php7.2.10/bin/php
 PHP config     : /Applications/MAMP/bin/php/php7.2.10/conf/php.ini
 PHP OS         : Darwin
 Drush script   : /Users/joachim/Sites/_sandbox/example-drush-extension/vendor/drush/drush/drush
 Drush version  : 9.6.2
 Drush temp     : /tmp
 Drush configs  : /Users/joachim/Sites/_sandbox/example-drush-extension/vendor/drush/drush/drush.yml
                  /Users/joachim/Sites/_sandbox/example-drush-extension/sut/drush/drush.yml
 Drupal root    : /Users/joachim/Sites/_sandbox/example-drush-extension/sut/web
 Site path      : sites/default