"Fatal error: Unsupported operand types" when dndu not activated for content type

I found out when the error appears:
- create a content type with e.g. multivalue Image field.
- create a node
- install dndu;
- edit the node ==> error.
It seems you MUST edit all relevant content types. If the dndu-fields are not set, the error appears.
Can you change the module t: if field is empty, then dndu is not activated?