"TypeError: Cannot read properties of undefined (reading 'regions')"

### Version

5.5.0

### Link to Minimal Reproduction

https://codesandbox.io/p/sandbox/echarts-basic-example-template-mpfz1s

### Steps to Reproduce

### Current Behavior

5.5 Errors reported above, errors reported below 5.5

### Expected Behavior

Expected Behavior

### Environment

```markdown
- OS:
- Browser:
- Framework:
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### Any additional comments?

_No response_

Reproduce the error using the linked CodeSandbox and compare behavior in ECharts 5.5.0 with a version below 5.5. Trace the undefined value associated with the `regions` access and identify the affected chart configuration. Done means the reproduction no longer throws this TypeError while retaining the expected chart behavior.

Written by the indexing model from the issue text.