REGRESSION: error message when defining new type

Steps to reproduce:

Defined a new custom compound.
Defined a new document type.
update all content
edited the document type and added the custom compound, done
received error message: jcr:predecessors have no value

it is possible to click done again and the type is saved

When editing a document instance similar behavior is exposed. Sometimes the error message is not displayed, but 'done' does not react.