Update allUnary logic

Author: pookjw

Sources/OpenSwiftUICore/Layout/Dynamic/DynamicContainer.swift

@@ -374,13 +374,15 @@ struct DynamicContainerInfo<Adapter>: StatefulRule, AsyncAttribute, ObservedAttr
                 var precedingCount: Int32 = 0
                 var allUnary = true
                 for index in 0..<inusedCount {
+                    info.indexMap[info.items[index].uniqueId] = index
                     let item = info.items[index]
-                    info.indexMap[item.uniqueId] = index
                     item.precedingViewCount = precedingCount
                     allUnary = allUnary && item.viewCount == 1
-                    info.allUnary = allUnary
-                    precedingCount &+= item.viewCount
+                    if index != inusedCount {
+                        precedingCount &+= item.viewCount
+                    }
                 }
+                info.allUnary = allUnary
             }
             precondition(info.indexMap.count == inusedCount, "DynamicLayoutItem identifiers must be unique.")
             if hasDepth {