使用dagre布局时，layer控制节点层级布局错乱

[zhl0916]

Describe the bug

使用dagre布局，layer控制节点层级，首次出现同级节点之间有连线的会导致布局失败

Your Example Website or App

https://g6.antv.antgroup.com/manual/middle/elements/methods/multi-line#gatsby-focus-wrapper

Steps to Reproduce the Bug or Issue

无

Expected behavior

布局失败 期望结果

Screenshots or Videos

No response

Platform

• OS: [e.g. macOS, Windows, Linux]
• Browser: [e.g. Chrome, Safari, Firefox]
• Version: [e.g. 91.1]

Additional context

No response