PHP error: Call to a member function id() on null

I have updated the code as per solution provided & added patch, please review.

Patch looks good

Change looks good.

However under what situation are we arriving at this condition?

I created a node, embedded it in an article page, then deleted the node.

When I load the article page I see this:

Code gets stopeed here:

In the error logs I get a proper log:

  2    20/Nov 14:06   entity_embed   Error      Drupal\entity_embed\Exception\EntityNotFoundException: Unable to load embedded node entity 593344e1-23fc-4524-8a8e-aadefe70f43a. in Drupal\entity_embed\Plugin\Filter\EntityEmbedFilter->process() (line 174  
                                                of /app/web/modules/contrib/entity_embed/src/Plugin/Filter/EntityEmbedFilter.php).                                                                                                                            

So we would need some steps to reproduce the issue first.

The issue can be reproduced in the following way:
- Embed content A inside content B
- Delete content A
- Edit content B
- Now click on edit button for embedded content.
- See the error mentioned in the issue description in the log.

I applied the patch and checked.

We see the same popup that we see when we click on the embed button.