🎨 Fix kanban attrView followup (#16277)

* fix: more robust fix for kanban empty groups error
- followup for handling of edge cases that cause "Cannot read properties of undefined (reading 'forEach')" error in renderKanban
- always apply preferred group key logic whenever kanban has an empty group key

* 🎨 Clean code

---------

Co-authored-by: D <845765@qq.com>

kernel/model/attribute_view_render.go

@@ -90,7 +90,15 @@ func renderAttributeView(attrView *av.AttributeView, nodeID, viewID, query strin
 func renderAttributeViewGroups(viewable av.Viewable, attrView *av.AttributeView, view *av.View, query string, page, pageSize int, groupPaging map[string]interface{}) (err error) {
 	groupKey := view.GetGroupKey(attrView)
 	if nil == groupKey {
-		return
+		if view.LayoutType == av.LayoutTypeKanban {
+			preferredGroupKey := getKanbanPreferredGroupKey(attrView)
+			group := &av.ViewGroup{Field: preferredGroupKey.ID}
+			setAttributeViewGroup(attrView, view, group)
+			av.SaveAttributeView(attrView)
+			groupKey = view.GetGroupKey(attrView)
+		} else {
+			return
+		}
 	}
 
 	// 当前日期可能会变，所以如果是按日期分组则需要重新生成分组