TypeError: Argument 1 passed to Drupal\Core\Form\FormState::setError() must be of the type array, string given

Problem/Motivation

When a previous button is implemented and no fields are filled in on the current step of the form, an error is triggered as stated in the title.

The full error log is as follows:

TypeError: Argument 1 passed to Drupal\Core\Form\FormState::setError() must be of the type array, string given, called in /var/www/html/docroot/modules/contrib/multistep_form_framework/src/Form/MultiStepFormBase.php on line 260 in Drupal\Core\Form\FormState->setError() (line 1093 of /var/www/html/docroot/core/lib/Drupal/Core/Form/FormState.php)
#0 /var/www/html/docroot/modules/contrib/multistep_form_framework/src/Form/MultiStepFormBase.php(260): Drupal\Core\Form\FormState->setError('field_horse_typ...', Object(Drupal\Core\StringTranslation\TranslatableMarkup))

Rather than the form element being passed to FormState_setError, only the field name is being passed and so the error is triggered. This is fixed by simply changing $form_state->setError to $form_state->setErrorByName. Will attach a patch.