physics.c: can_collide now checks for object_is_valid before comfirming other variables

src/corelib/physics.c

@@ -24,7 +24,7 @@ void object_broadcast_collision(object_t* this, object_t* other) {
 	}
 }
 short can_collide(const object_t* this) {
-	return this->active && this->enabled;
+	return object_is_valid(this) && this->enabled;
 }
 
 static inline