[Bug] 桑基图 source为0的节点，tooltip没有标签

[SuSunSam]

Version

2.0.16

Link to Minimal Reproduction

https://www.visactor.com/vchart/playground?specId=2784301030&timestamp=1772454679754&version=2.0.16&theme=light

Steps to Reproduce

`const spec = {
type: 'sankey',
data: [
{
values: [
{
nodes: [
{ nodeName: "Agricultural 'waste'" },
{ nodeName: 'Bio-conversion' },
{ nodeName: 'CCCCC' },
{ nodeName: 'DDD' },
],
links: [
{ source: 0, target: 2, value: 124.729 },
{ source: 2, target: 3, value: 124.729 },
]
}
]
}
],
categoryField: 'nodeName',
valueField: 'value',
sourceField: 'source',
targetField: 'target',

label: {
visible: true,
style: {
fontSize: 10
}
},

};

const vchart = new VChart(spec, { dom: CONTAINER_ID });
vchart.renderSync();

// Just for the convenience of console debugging, DO NOT COPY!
window['vchart'] = vchart;`

Current Behavior

桑基图 source为0的节点，tooltip没有标签

Expected Behavior

桑基图 source为0的节点，tooltip显示标签

Environment

- OS:
- Browser:
- Framework:

Any additional comments?

No response

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Title: [Bug] The node in the Sankey diagram where the source is 0, the tooltip has no label