Fatal errors when configuring Shadowbox

Multiple errors (when the info files are correct and the path is correct as noted in issues 2807781 and 2807791) when trying to configure the module.

I don't the correct way to do this; since these are multiple issues in the same file, should I file an issue report for each one or can I combine them in one file?
I've chosen the latter :)

"Declaration of Drupal\shadowbox\Form\ShadowboxGlobalSettingsForm::buildForm() must be compatible with Drupal\Core\Form\FormInterface::buildForm"
"Declaration of Drupal\shadowbox\Form\ShadowboxGlobalSettingsForm::submitForm() must be compatible with Drupal\Core\Form\FormInterface::submitForm(array &$form, Drupal\Core\Form\FormStateInterface $form_state)"
"Class Drupal\shadowbox\Form\ShadowboxGlobalSettingsForm contains 1 abstract method and must therefore be declared abstract or implement the remaining methods"
"Call to undefined function Drupal\shadowbox\Form\l()"
"LogicException: You are not allowed to use css in #attached."