Issue Overview

Update of a post repeatedly fails after inserting a Latest Post Block and the following error in the Editor
wp/wp-content/plugins/gutenberg/blocks/library/latest-posts/index.php on line 55

Steps to Reproduce (for bugs)

1. Create new post
2. Add Paragraph, Images, Gallery Blocks
3. Update -> Success
4. Add Latest Post Block
5. Update -> fails
6. Remove latest post
7. Update -> success

Expected Behavior

Update succeeds after adding a latest post block

Current Behavior

Update fails after adding latest post block

Possible Solution

The latest post block seems to regard the currently edited post (where user is currently adding the latest post block) already as a latest post, since it is listet in the latest post preview which might create a loop.