Error: Call to a member function getConfigDependencyName() on null

Problem/Motivation

Getting `Error: Call to a member function getConfigDependencyName() on null` on pages.

Not really sure what got me in this state, walked away and it was there when I came back.

Looking at the code it seems clear _how_ it can happen though.

      // If the dependencies are entities we need to convert them into objects.
      if ($type == 'config' || $type == 'content') {
        $affected_dependencies[$type] = array_map(function ($name) use ($type) {
          if ($type == 'config') {
            return $this->loadConfigEntityByName($name);
          }
          else {
            // Ignore the bundle.
            [$entity_type_id,, $uuid] = explode(':', $name);
            return $this->entityRepository->loadEntityByConfigTarget($entity_type_id, $uuid);
          }
        }, $affected_dependencies[$type]);
      }

     // ...
    // Key the entity arrays by config dependency name to make searching easy.
    foreach (['config', 'content'] as $dependency_type) {
      $affected_dependencies[$dependency_type] = array_combine(
        array_map(function ($entity) {
          return $entity->getConfigDependencyName();
        }, $affected_dependencies[$dependency_type]),
        $affected_dependencies[$dependency_type]
      );
    }

Since loadConfigEntityByName can return null and the later result uses the value without checking any weirdness in the dependency list can trigger an error.

Steps to reproduce

Proposed resolution

A fix might be as easy as an array filter? It seems like if the load failed, no future code is going to be able to interact with it. Alternatively though, we could just pass the names around and skip the load? its not immediately clear why we need to load the entity before mapping back to the entity name.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet