TYPO3 Core

In TYPO3 7.4 FAL or the new FormEngine have a bug when deleting a FAL Relation.

Deleting FAL relation from pages media:
When deleting a FAL relation (e.g. an image) from page media, in backend a javascript error appears:

The file relation disappears in backend and also the relation in database. The number in pages media, which had the value "1" before, should now be "0", but even without having a relation this value does not update.

Deleting FAL relation from Flexform:
The same javascript error appears, but the FAL relation remains visible until you save the record. Then the deleted relation is gone, but also here the value "1" remains in flexform.