fix(line): avoid crash when visualMap piecewise produces no in-range stops

src/chart/line/LineView.ts

@@ -323,7 +323,14 @@ function getVisualGradient(
     const stopLen = colorStops.length;
     const outerColors = visualMeta.outerColors.slice();
 
-    if (stopLen && colorStops[0].coord > colorStops[stopLen - 1].coord) {
+    if (stopLen && (
+        colorStops[0].coord > colorStops[stopLen - 1].coord
+        // When stops collapse to the same coord (e.g. a piecewise visualMap with
+        // a single half-infinite piece produces two boundary stops at the same
+        // value), the coord comparison gives no signal — fall back to the axis
+        // direction so we still flip on an inverted axis. See #18066.
+        || (colorStops[0].coord === colorStops[stopLen - 1].coord && axis.inverse)
+    )) {
         colorStops.reverse();
         outerColors.reverse();
     }
@@ -337,6 +344,13 @@ function getVisualGradient(
             ? (outerColors[1] ? outerColors[1] : colorStops[stopLen - 1].color)
             : (outerColors[0] ? outerColors[0] : colorStops[0].color);
     }
+    if (!inRangeStopLen) {
+        // No color stops at all (e.g. a visualMap piecewise piece producing
+        // a fully [-Infinity, Infinity] interval, like `pieces: [{ lte: null }]`).
+        // Fall back to a single outer color or transparent so we don't crash
+        // on `colorStopsInRange[0].coord` below. See #18066.
+        return outerColors[0] || outerColors[1] || 'transparent';
+    }
 
     const tinyExtent = 10; // Arbitrary value: 10px
     const minCoord = colorStopsInRange[0].coord - tinyExtent;

src/component/visualMap/PiecewiseModel.ts

@@ -370,12 +370,28 @@ class PiecewiseModel extends VisualMapModel<PiecewiseVisualMapOption> {
                 valueState = visualMapModel.getValueState(representValue);
             }
             const color = getColorVisual(representValue, valueState);
-            if (interval[0] === -Infinity) {
+            const lowInf = interval[0] === -Infinity;
+            const highInf = interval[1] === Infinity;
+            if (lowInf) {
                 outerColors[0] = color;
             }
-            else if (interval[1] === Infinity) {
+            if (highInf) {
                 outerColors[1] = color;
             }
+            // Emit the finite edge(s) as stops as well, so consumers know where
+            // a half-infinite interval ends (e.g. `pieces: [{lte: 10}]` should
+            // still report a boundary at 10). When the interval is fully infinite
+            // there is no finite edge to record, so only `outerColors` is set.
+            // See #18066.
+            if (lowInf && highInf) {
+                return;
+            }
+            if (lowInf) {
+                stops.push({value: interval[1], color: color});
+            }
+            else if (highInf) {
+                stops.push({value: interval[0], color: color});
+            }
             else {
                 stops.push(
                     {value: interval[0], color: color},