ErrorDataSetRenderer: fix error surfaces for inexact array cache

The compaction routine for the error surface polygon vectors was not
correctly handling arrays bigger than the requested size, leading to
wrong error surfaces. This passes the actual expected size to the
compaction method so it can correctly move the 2 halves of the data
behind each other.

chartfx-chart/src/main/java/io/fair_acc/chartfx/renderer/spi/ErrorDataSetRenderer.java

@@ -417,8 +417,8 @@ protected void drawErrorSurfaceNaNCompatible(final GraphicsContext gc, final Dat
                 count++;
             } else if (count != 0) {
                 // remove zeros and plot intermediate segment
-                compactVector(xValuesSurface, count);
-                compactVector(yValuesSurface, count);
+                compactVector(xValuesSurface, nPolygoneEdges, count);
+                compactVector(yValuesSurface, nPolygoneEdges, count);
 
                 gc.fillPolygon(xValuesSurface, yValuesSurface, 2 * count);
                 count = 0;
@@ -427,8 +427,8 @@ protected void drawErrorSurfaceNaNCompatible(final GraphicsContext gc, final Dat
         if (count > 0) {
             // swap y coordinates at mid-point
             // remove zeros and plot intermediate segment
-            compactVector(xValuesSurface, count);
-            compactVector(yValuesSurface, count);
+            compactVector(xValuesSurface, nPolygoneEdges, count);
+            compactVector(yValuesSurface, nPolygoneEdges, count);
             if (count > 4) {
                 final double yTmp = yValuesSurface[count - 1];
                 yValuesSurface[count - 1] = yValuesSurface[count];
@@ -802,9 +802,9 @@ protected static void drawPolyLineStairCase(final GraphicsContext gc, final Data
         gc.restore();
     }
 
-    private static void compactVector(final double[] input, final int stopIndex) {
+    private static void compactVector(final double[] input, final int inputLength, final int stopIndex) {
         if (stopIndex >= 0) {
-            System.arraycopy(input, input.length - stopIndex, input, stopIndex, stopIndex);
+            System.arraycopy(input, inputLength - stopIndex, input, stopIndex, stopIndex);
         }
     }