deleteEntityPathAll calls getInternalPath on potentially unrouted url

Problem/Motivation

I'm using a bundle class to override the toUrl() method on a particular node type. In particular, there's a link field that, if populated, will be used by the toUrl() method. The reason is that we want to allow cards to link to internal or external links (or no link whatsoever) as elegantly as possible. The code looks like this:

  public function toUrl($rel = 'canonical', array $options = []) {
    if ($rel === 'canonical') {
      if (!empty($this->field_link->uri)) {
        return Url::fromUri($this->field_link->uri);
      }
      else {
        return Url::fromRoute('<nolink>');
      }
    }
    return parent::toUrl($rel, $options);
  }

This exposed some bugs in core (#3342398: Path module calls getInternalPath without checking if the url is routed) and Redirect (#3342409: redirect_form_node_form_alter calls getInternalPath on potentially unrouted url) and finally (hopefully finally) within Pathauto. The problem in Pathauto appears when one tries to delete a node (or other entity) that has an external canonical url. Upon doing so I get an exception:

Drupal\Core\Entity\EntityStorageException: Unrouted URIs do not have internal representations. in Drupal\Core\Entity\Sql\SqlContentEntityStorage->delete() (line 761 of core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php).

Drupal\pathauto\AliasStorageHelper->deleteEntityPathAll(Object) (Line: 101)
pathauto_entity_delete(Object)

Steps to reproduce

See above

Proposed resolution

Add a check could be added to the already long list of checks in pathauto_entity_delete to see if the url is routed.

Alternative the check could be added to AliasStorageHelper::deleteEntityPathAll.

Remaining tasks

User interface changes

N/A

API changes

N/A

Data model changes

N/A