Javascript Tree VueDragable，无法将节点拖动到不带'；我没有孩子

我无法将节点拖动到没有子节点的节点。它在我的嵌套树代码上运行良好：

<div class="child">
            <draggable 
                :list="trees.childs" 
                :options="{animation: 200, group:'dragtree'}"
                :move="onMove"
                @end="onEnd">
                <graph
                    v-if="open"
                    v-for="tree in trees.childs"
                    :key="tree.root"
                    :trees="tree">
                </graph>
            </draggable>
        </div>

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我面临着同样的问题，我面临着同样的问题。

onEnd:function(event){
        this.D_related.childs.push({root : this.D_dragged.root, depth : this.D_related.depth+1, childs: this.D_dragged.childs})
    },
onMove: function(event){
        console.log("Move", event)
        this.D_dragged = event.draggedContext.element
        this.D_related = event.relatedContext.element
        return 
    },