Editor::getFilterFormat() shouldn't cause fatal error before Editor saved

Problem/Motivation

I keep finding myself writing code like this:

  if (!$editor->hasAssociatedFilterFormat()) {
    return;
  }

  $format = $editor->getFilterFormat();
  if (empty($format)) {
    return;
  }

I'd like to be able to just do this:

  $format = $editor->getFilterFormat();
  if (empty($format)) {
    return;
  }

If you do this before an editor object is saved, you get a frustrating fatal error about trying to load an entity with a NULL id.

This usually happens calling code in a subroutine at '/admin/config/content/formats/add'.

I believe you should not get a fatal error when calling $editor->getFilterFormat() before the entity is saved. It should return NULL.

The interface even says it can return NULL, but the ::getFilterFormat() in Editor doesn't really allow for this:

  /**
   * Returns the filter format this text editor is associated with.
   *
   * This could be NULL if the associated filter format is still being created.
   * @see hasAssociatedFilterFormat()
   *
   * @return \Drupal\filter\FilterFormatInterface|null
   */
  public function getFilterFormat();

Proposed resolution

Change this code:

  /**
   * {@inheritdoc}
   */
  public function hasAssociatedFilterFormat() {
    return $this->format !== NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function getFilterFormat() {
    if (!$this->filterFormat) {
      $this->filterFormat = \Drupal::entityTypeManager()->getStorage('filter_format')->load($this->format);
    }
    return $this->filterFormat;
  }

To this:

  /**
   * {@inheritdoc}
   */
  public function hasAssociatedFilterFormat() {
    return $this->format !== NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function getFilterFormat() {
    if (!$this->hasAssociatedFilterFormat()) {
      return NULL;
    }
    if (!$this->filterFormat) {
      // Should we add a try catch here?
      return \Drupal::entityTypeManager()->getStorage('filter_format')->load($this->format);
    }
    return NULL;
  }

If this change is made, there are places where calling ::hasAssociatedFilterFormat() will be unnecessary.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet