DrawingController does not show sketched image

[Sesa1988]

• Save the json
• create a column with the whiteboard widget
• init the data var draw = WhiteboardDraw.fromJson(widget.data ?? newData); drawController = new DrawingController(draw: draw);

result: a white board shows up, after clicking on it a exception is thrown and after that the paths are loaded.

exception: he following NoSuchMethodError was thrown while handling a gesture: The getter '_value' was called on null. Receiver: null Tried calling: _value