[Bug] taro-vchart misses function-only spec updates and throws on cyclic specs

Version

@visactor/taro-vchart on develop at 0750d74cd6ea734e66897876506c78ca12680676

Link to Minimal Reproduction

The update guards in both of these components reproduce the comparison behavior directly:

• packages/taro-vchart/src/components/general-chart/index.tsx
• packages/taro-vchart/src/components/web-chart/index.tsx

For example, JSON.stringify({ formatter: () => 'old' }) and JSON.stringify({ formatter: () => 'new' }) are both {}. A cyclic object throws from JSON.stringify.

Steps to Reproduce

1. Render a Taro VChart with a spec containing a formatter or another supported callback.
2. Update the component with a new callback while leaving the serializable fields unchanged.
3. Alternatively, update with a spec containing a circular reference.

Current Behavior

Both componentDidUpdate implementations use JSON.stringify to decide whether the spec changed. Function-only changes compare equal, so updateSpec is not called. Circular specs throw during the lifecycle method instead of reaching VChart.

Expected Behavior

Spec updates should use a comparison strategy that supports VChart's valid function-valued options and does not throw on cyclic input.

Environment

• OS: Windows 11
• Node.js: 20.20.2 and 24.14.1
• Package: @visactor/taro-vchart

Any additional comments?

The comparison has existed since the component's initial implementation, and this package currently has no unit tests covering update behavior. A fix should choose and test the intended function-diff and cyclic-object semantics rather than replacing the guard without measuring update cost.

Related: #4254 reports that serializable spec updates do not refresh under Taro 4.x. This report isolates two comparator behaviors that are present in the wrapper code independent of Taro version: function-only changes compare equal and cyclic input throws. #4254 has no linked PR or commit and does not mention either comparator case.

I searched all 4,627 open/closed issues and pull requests locally after fetching their current metadata, including Taro spec updates, JSON.stringify, function specs, circular specs, and general-chart; I also reviewed the file history and repository Discussions (none). Apart from the broader #4254 above, I did not find an existing report or fix for these two cases.

Start with componentDidUpdate in packages/taro-vchart/src/components/general-chart/index.tsx and packages/taro-vchart/src/components/web-chart/index.tsx, then inspect how updateSpec is called. Add tests for function-only changes and cyclic specs, choosing and documenting the intended comparison semantics and update cost. Done means valid callback changes trigger updateSpec and cyclic input no longer throws.