GACK on save when using dynamic picklist of collaborationGroup as design attribute in lightning app builder

Question

I've built a simple lightning component that displays the chatter feed and publisher for a single chatter group. The component has an attribute that allows setting CollaborationGroupId in lightning app builder.

This all works fine if I set up the design file so that I can manually enter an Id.

Now i'm trying to use the dynamicpicklist class to generate a list of Chatter Groups. The basic functionality works, ie a picklist of groups is generated in the app builder, but the component throws an uncaught error on save. Note that preview works properly, and the preview updates to reflect the selected group - but on save I get a gack.

We had trouble processing the request. We've reported the problem to Customer Support with error ID: -583343216

Is there any special trick to this? The docs dont indicate that anything is required beyond setting the datasource in the design file to the apex class, but wanted to check in case anyone has figured this out before I file a case.

Code below

COMPONENT

<aura:component implements="force:appHostable,flexipage:availableForAllPageTypes">
    <aura:attribute name="groupId" default="select one" type="String" required="true" description="18 char id" />
    <forceChatter:publisher context="RECORD" recordId="{!v.groupId}" />
    <forceChatter:feed type="Record" subjectId="{!v.groupId}" feedDesign="DEFAULT"/>
</aura:component>

DESIGN

<design:component >
<design:attribute name="groupId" default="Select Group" label="Select Group" datasource="apex://GroupPicklist" description="dynamic picklist" placeholder="select group" />             
</design:component>

APEX CLASS

 global class GroupPicklist extends VisualEditor.DynamicPickList{

        list<CollaborationGroup> groupList = new list<CollaborationGroup>([Select Id,Name FROM CollaborationGroup WHERE IsArchived = FALSE]);

        global override VisualEditor.DataRow getDefaultValue(){
            VisualEditor.DataRow defaultValue = new VisualEditor.DataRow('Select One','SELECTONE');      
            IF(grouplist.size() > 0){
            string groupName = groupList[0].Name;
            string groupId = groupList[0].Id;
            VisualEditor.DataRow populatedValue = new VisualEditor.DataRow(groupName,groupId);
            return populatedValue;
            }           
            ELSE{
                return defaultValue;
            }
        }
        global override VisualEditor.DynamicPickListRows getValues() {
            VisualEditor.DynamicPickListRows  myValues = new VisualEditor.DynamicPickListRows();
                        list<VisualEditor.DataRow> DataRowList = new list<VisualEditor.DataRow>();
            FOR (CollaborationGroup cg : groupList){            
                string cgName = cg.Name;
                string cgId = cg.Id;
                VisualEditor.DataRow dr = new VisualEditor.DataRow(cgName,cgId);                
                DataRowList.add(dr);
            }
            myValues.addAllRows(DataRowList);
            return myValues;
        }
    }

Answer 1

There is now a known issue for this. Will update once resolved.