Steps to reproduce:

• Run only author instance of magnolia
• Create decoration for publishing-core in /categories-app/decorations/publishing-core/config.yaml with:

     receivers:
       magnoliaPublic8080:
         enabled: false

• Publish/unpublish any content, the decoration is applied => no exception is thrown
• Remove the decoration
• Publish/unpublish any content, the config from the decoration is still applied => no exception is thrown but original config of publishing-core should be applied and exception should be thrown.
• One can also use Definitions App to check that whole magnoliaPublic8080 node disappeared at all after removing decoration yaml file.

Default publishing-core config contains configuration for receivers like below:

receivers:
  magnoliaPublic8080:
    enabled: true