Fix corrupted state due to custom extensions causing downstream errors in destroyDrawable (TurboWarp#28)

Certain custom extensions, such as SharkPool Layer Control, thoroughly corrupt internal state by rearranging drawables outside the layer they ought to belong to. This breaks a lot of things in various ways. One of the things it breaks is the loop where we try to find the drawable by checking where it's layer start and ends. The impact of this corruption is severe enough that it's best if we work around it.

Author: GarboMuffin

src/RenderWebGL.js

@@ -832,10 +832,25 @@ class RenderWebGL extends EventEmitter {
         if (index < endIndex) {
             this._drawList.splice(index, 1);
             this._updateOffsets('delete', currentLayerGroup.groupIndex);
-        } else {
-            log.warn('Could not destroy drawable that could not be found in layer group.');
             return;
         }
+
+        // Certain custom extensions, such as SharkPool Layer Control, thoroughly corrupt internal state
+        // by rearranging drawables outside the layer they ought to belong to. This breaks a lot of things
+        // in various ways. One of the things it breaks is the loop above where we try to find the drawable
+        // by checking where its layer starts and ends. The impact of this corruption is severe enough that
+        // it's best if we work around it.
+        index = this._drawList.indexOf(drawableID);
+        if (index === -1) {
+            log.warn('Could not destroy drawable that could not be found in draw list.');
+            return;
+        }
+        this._drawList.splice(index, 1);
+        for (const groupName of this._groupOrdering) {
+            if (this._layerGroups[groupName].drawListOffset > index) {
+                this._layerGroups[groupName].drawListOffset--;
+            }
+        }
     }
 
     /**