fix(rose): clamp the area-proportion radicand against negative cumulatives

Difference-style comparisons can drive the running total negative, which
turned the area-mode sqrt into a NaN radius. Clamp the radicand at 0 so a
negative cumulative collapses to the center instead.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: claude

superset-frontend/plugins/plugin-chart-echarts/src/Rose/transformProps.ts

@@ -92,8 +92,12 @@ export default function transformProps(
     let previousOuter = 0;
     const entries = (datum[time] ?? []).map(entry => {
       cumulative += entry.value;
+      // Area encoding is undefined for a negative cumulative (possible
+      // with difference-style comparisons); clamp the radicand at 0 so a
+      // negative running total collapses to the center rather than
+      // producing a NaN radius.
       const outer = roseAreaProportion
-        ? Math.sqrt(cumulative / maxSum)
+        ? Math.sqrt(Math.max(0, cumulative / maxSum))
         : cumulative;
       const increment = outer - previousOuter;
       previousOuter = outer;

superset-frontend/plugins/plugin-chart-echarts/test/Rose/transformProps.test.ts

@@ -149,3 +149,23 @@ test('handles empty results without crashing', () => {
   expect(periods).toEqual([]);
   expect((echartOptions as any).series).toEqual([]);
 });
+
+test('area proportion clamps negative cumulatives instead of yielding NaN', () => {
+  // difference-style comparisons can produce negative values
+  const negatives = [
+    { __timestamp: T1, 'sum__num, East': -30, 'sum__num, West': 10 },
+  ];
+  const props = new ChartProps({
+    width: 800,
+    height: 600,
+    formData: { ...formData, roseAreaProportion: true },
+    theme: supersetTheme,
+    queriesData: [{ data: negatives }],
+    hooks: {},
+  }) as unknown as EchartsRoseChartProps;
+  const { echartOptions } = transformProps(props);
+  const { series } = echartOptions as any;
+  series.forEach((s: any) =>
+    s.data.forEach((d: any) => expect(Number.isNaN(d.value)).toBe(false)),
+  );
+});