fix: answer an empty checklist with an empty items list

controllers/api/checklists.go

@@ -72,7 +72,7 @@ type checklistJSON struct {
 	Description *string              `json:"description"`
 	SortOrder   int                  `json:"sort_order"`
 	Progress    checklistProgress    `json:"progress"`
-	Items       []checklistItemJSON  `json:"items,omitempty"`
+	Items       *[]checklistItemJSON `json:"items,omitempty"`
 	CreatedAt   string               `json:"created_at"`
 	UpdatedAt   string               `json:"updated_at"`
 }
@@ -319,10 +319,11 @@ func checklistsJSON(db *gorm.DB, userID uint, lists []models.Checklist, withItem
 			item.Progress.add(it)
 		}
 		if withItems {
-			item.Items = items[c.ID]
-			if item.Items == nil {
-				item.Items = []checklistItemJSON{}
+			list := items[c.ID]
+			if list == nil {
+				list = []checklistItemJSON{}
 			}
+			item.Items = &list
 		}
 		out = append(out, item)
 	}