10.2.0 database update failes with "Error: Call to a member function getConfigDependencyName() on null"

Problem/Motivation

When running the database update script after updating from 10.1.7 to 10.2.0 I get the following error:

In ProcessBase.php line 171:
                                                                                                          
  Unable to decode output into JSON: Syntax error                                                         
                                                                                                          
  Error: Call to a member function getConfigDependencyName() on null in Drupal\editor\Entity\Editor->cal  
  culateDependencies() (line 122 of ../web/core/modules/editor/src/Entity/Edit  
  or.php). 

Can anyone help me? Thank you very much!