[Bug] Chord Diagram Fails to Render with Sparse, Purely Directed, and Disconnected Data

### Version

5.5.0

### Link to Minimal Reproduction

https://echarts.apache.org/examples/zh/editor.html?code=PYBwLglsB2AEC8sDeBYAULWkwBsCmAXMuppmHgB5hEDkAshAOYBOAhpDLAMIAWwzAE1gARCKxasAtjQA0JUvgBm1WDQDGeaOWY15AXzkYswYDkggiqIwfkBnPMwh5bRANpXSWAJ4hCqtXyCsvKYAuysbiGeyLDQUn4ARFwATAmwBjFxkolcAIy5aRlIsfFESbkA7IWG0aTFWTnJACzVmaWwSckArK317UldAJzVUZ592WVcFQAMhVEAujWkkuyOFJFGnq7TMrA7e7v7R4eLo7Dbh5cH17knS1vH18lXR6ebpBfXj99vta63XxeL1-0U-3yBexBW2egNhrwWSz083QegA3EA

### Steps to Reproduce

Open the "Link to Minimal Reproduction" provided above.
Observe the chart rendering area.

### Current Behavior

The Chord Diagram fails to render, appearing as a blank container. No errors are thrown in the browser's developer console (it fails silently). Other charts on the same page, using data from the same source, render correctly.

### Expected Behavior

The Chord Diagram should render successfully, displaying the nodes and the directed, sparse connections (chords) between them, even when the data represents a disconnected graph.

### Environment

```markdown
- OS:Windows 11 64-bit
- Browser:
Google Chrome: 138.0.7204.101
Microsoft Edge: 138.0.3351.77
Opera One: 120.0.5543.61
- Framework:N/A
```

### Any additional comments?

The bug appears to be triggered by a specific data structure passed to the Chord Diagram component. The rendering failure occurs when the data represents a graph that is both:

Purely Directed: All connections are one-way (if matrix[i][j] > 0, then matrix[j][i] === 0).

Disconnected: The graph consists of multiple separate components with no links between them.

This suggests the issue is not a user-side code error but rather an unhandled edge case within the ECharts library's layout algorithm for this specific chart type.