fix(model): guard against null data in getDataParams and event handler

[davesecops]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Adds null guards to getDataParams() and its 6 chart-specific overrides to prevent TypeErrors when getData() returns null on disposed series during mouse events.

Fixed issues

• Cannot read property 'getRawIndex' of undefined #9402: Cannot read property 'getRawIndex' of undefined (pie, reported 2018)
• [Bug] get error [undefined (reading 'getRawIndex') ] when click on stackline chart #16998: Same error on stacked line chart click (open)
• [Bug] TypeError in getDataParams when getData() returns null on disposed series #21535: Comprehensive analysis of the root cause and all affected code paths

Details

Before: What was the problem?

When a chart series is disposed (via echarts.dispose(), component unmount in React/Vue/Angular, setOption with notMerge, or toolbox restore), SeriesModel.getData() returns null/undefined. The comment in Series.ts explicitly acknowledges this:

// When series is not alive (that may happen when click toolbox
// restore or setOption with not merge mode), series data may
// be still need to judge animation or something when graphic
// elements want to know whether fade out.
return inner(this).data;  // ← can be undefined

However, getDataParams() and its overrides unconditionally call methods on the result:

// dataFormat.ts — base method
const data = this.getData(dataType);
const rawDataIndex = data.getRawIndex(dataIndex);  // 💥 TypeError

// TreemapSeries.ts — override
const node = this.getData().tree.getNodeByDataIndex(dataIndex);  // 💥 TypeError

// PieSeries.ts — override
const data = this.getData();
data.each(data.mapDimension('value'), ...);  // 💥 TypeError

The primary crash trigger is the event handler in echarts.ts which calls getDataParams() during mousemove/mouseout events that fire on stale DOM elements after chart disposal. This affects all chart types in all frameworks where component lifecycle causes disposal during user interaction.

After: How does it behave after the fixing?

Three layers of defense:

1. Base method guard (src/model/mixin/dataFormat.ts):

const data = this.getData(dataType);
if (!data) {
    return {} as CallbackDataParams;
}

Returns {} when data is null — consistent with the existing fallback at echarts.ts:778 (dataModel.getDataParams(...) || {}). Protects all callers outside the event handler (tooltips, labels, visual pipeline).

2. Event handler guard (src/core/echarts.ts):

try {
    params = (dataModel && dataModel.getDataParams(...) || {}) as ECElementEvent;
} catch (e) {
    params = {} as ECElementEvent;
}

Wraps the highest-risk call site in try/catch, catching crashes from any chart override's getData() access.

3. Override guards (6 chart series files):
Each override now checks getData() before accessing chart-specific properties:

• TreemapSeries.ts — guards data.tree access
• SunburstSeries.ts — guards data.tree access
• TreeSeries.ts — guards data.tree access
• PieSeries.ts — guards data.each(), data.mapDimension() access
• FunnelSeries.ts — guards data.mapDimension(), data.getSum() access
• ChordSeries.ts — guards data.getName(), this.getGraph() access

This pattern follows existing precedent in the codebase — SeriesModel.getAllData() already null-guards getData():

const mainData = this.getData();
return mainData && mainData.getLinkedDataAll ? mainData.getLinkedDataAll() : [{ data: mainData }];

Document Info

• This PR doesn't relate to document changes

Misc

Security Checking

• This PR uses security-sensitive Web APIs.

ZRender Changes

• This PR depends on ZRender changes.

Related test cases or examples to use the new APIs

N/A — this is a defensive fix. A test case would require simulating chart disposal during mouse events (component unmount race condition).

Merging options

• Please squash the commits into a single one when merging.

Other information

This bug has been open since 2018 (#9402) and affects all chart types. It is the most commonly reported ECharts crash in React/Vue applications where charts are rendered in routed views. The fix is minimal (35 lines added across 8 files), safe (returns empty params matching existing fallback patterns), and follows internal precedent.

[echarts-bot]

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Please DO NOT commit the files in dist, i18n, and ssr/client/dist folders in a non-release pull request. These folders are for release use only.

[davesecops]

Superseded by #21537 (branch renamed to follow project convention fix-<issue_id>). Same fix + added unit tests.