Xeltalliv/clippingblending: Fix effect resetting on stopping project …

…and incorrect clipping box inheritance by clones (#1451)

1. In the past, stopping the project would visually reset effects, but
they were still there internally, causing clones to inherit them.
2. In the past, creating clone would always result in a clone with
clipping box. If the original sprite/clone did not have it, the newly
created clipping box would be represented as an empty object (instead of
null), which meant all of the required values were undefined. This
caused clone to turn invisible. [Originally reported on discord by @
cas_thekid](https://discord.com/channels/837024174865776680/1169100193749291008)

extensions/Xeltalliv/clippingblending.js

@@ -152,6 +152,8 @@
       const proto = vm.runtime.targets[0].__proto__;
       const osa = proto.onStopAll;
       proto.onStopAll = function () {
+        this.clipbox = null;
+        this.blendMode = "default";
         this.renderer.updateDrawableClipBox.call(
           renderer,
           this.drawableID,
@@ -168,7 +170,9 @@
       proto.makeClone = function () {
         const newTarget = mc.call(this);
         if (this.clipbox || this.blendMode) {
-          newTarget.clipbox = Object.assign({}, this.clipbox);
+          newTarget.clipbox = this.clipbox
+            ? Object.assign({}, this.clipbox)
+            : null;
           newTarget.blendMode = this.blendMode;
           renderer.updateDrawableClipBox.call(
             renderer,