[Bug]: 当节点类型为图片时，创建边的时候，点击图片，报错： TypeError: Cannot read properties of undefined (reading 'src')

### Describe the bug / 问题描述

当节点类型为图片时，创建边的时候，点击图片，报错： TypeError: Cannot read properties of undefined (reading 'src')
节点定义
```js
{
nodes: [
{
id: 'node-1',
style: { x: 50, y: 100, labelText: '路由器1', src: '/xxx.png'}
},
{
id: 'node-2',
style: { x: 150, y: 100, labelText: '路由器2', src: '/yyy.png }
}
],
edges: [{ id: 'edge-1', source: 'node-1', target: 'node-2' }]
}
```

### Reproduction link / 复现链接

_No response_

### Steps to Reproduce the Bug or Issue / 重现步骤

_No response_

### Version / 版本

Please select / 请选择

### OS / 操作系统

- [ ] macOS
- [x] Windows
- [ ] Linux
- [ ] Others / 其他

### Browser / 浏览器

- [ ] Chrome
- [ ] Edge
- [ ] Firefox
- [ ] Safari (Limited support / 有限支持)
- [ ] IE (Nonsupport / 不支持)
- [ ] Others / 其他

Start by reproducing the supplied graph with image nodes and trace edge creation when an image is clicked, using the reported undefined `src` error as the failure signal. No file, test, reproduction link, version, or acceptance condition is provided; confirm the affected entry point and add coverage so image-node edge creation completes without the error.

Written by the indexing model from the issue text.