I am getting the following when displaying a List Area (from the Dialogs examples) with an empty ListContent child component. It seems that the VerticalScrollLayoutElement class is trying to disable the scroll handle image while inside a Unity rebuild loop (Unity doesn't like it).
Error does not happen when the ListContent component has children.
Error does not happen if the ListContent didn't previously have children (i.e. the scrollbar has yet to be displayed).
I've circumvented the issue by commenting out the line (188) in VerticalScrollLayoutElement. Leaves a small visual artefact when there's an empty list, but I can live with it for now.
Here's the error:
Trying to remove Handle (UnityEngine.UI.Image) from rebuild list while we are already inside a rebuild loop. This is not supported.
MaterialUI.VerticalScrollLayoutElement:RefreshLayout() (at Assets/MaterialUI/Scripts/Common/VerticalScrollLayoutElement.cs:188)
MaterialUI.VerticalScrollLayoutElement:CalculateLayoutInputVertical() (at Assets/MaterialUI/Scripts/Common/VerticalScrollLayoutElement.cs:211)