Fixed objects which store Lua callback functions to avoid attempting to use dead coroutines when deleting the reference to the callback function. Should fix crashes when coroutines are mixed with those objects.

Also improved the performance of World:rayCast and World:queryBoundingBox.

src/modules/physics/box2d/Body.h

@@ -48,7 +48,7 @@ class Fixture;
 struct bodyudata
 {
 	// Reference to arbitrary data.
-	Reference *ref;
+	Reference *ref = nullptr;
 };
 
 /**