Exception when configuring module

When the module is enabled, it's not possible to configure it. When 'admin/config/media/shadowbox' is called, the page shows an "unexpected error". The log shows:
InvalidArgumentException: Class "\Drupal\shadowbox\Form\ShadowboxGlobalSettingsForm" does not exist

This is due to the fact that the path to ShadowboxGlobalSettingsForm.php is not correct. It's /lib/Drupal/shadowbox/Form/ShadowboxGlobalSettingsForm.php and should be /src/Form/ShadowboxGlobalSettingsForm.php.