From 2d54b72882551d45ccff7c5f8c003e30e16b6d09 Mon Sep 17 00:00:00 2001
From: tobspr <tobias.springer1@googlemail.com>
Date: Mon, 27 Jul 2020 13:49:40 +0200
Subject: [PATCH] Add checks to stacking logic

---
 src/js/game/shape_definition.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/js/game/shape_definition.js b/src/js/game/shape_definition.js
index 3a777f6f..a9e9e7ba 100644
--- a/src/js/game/shape_definition.js
+++ b/src/js/game/shape_definition.js
@@ -570,10 +570,12 @@ export class ShapeDefinition extends BasicSerializableObject {
             const bottomShapeLayer = mergedLayers[layerMergingAt];
             const topShapeLayer = topShapeLayers[layer];
             for (let quad = 0; quad < 4; quad++) {
+                assert(!(bottomShapeLayer[quad] && topShapeLayer[quad]), "Shape merge: Sub shape got lost");
                 bottomShapeLayer[quad] = bottomShapeLayer[quad] || topShapeLayer[quad];
             }
         }
 
+        // Limit to 4 layers at max
         mergedLayers.splice(4);
 
         return new ShapeDefinition({ layers: mergedLayers });