Current questions and answers regarding the map editor.

This error occurs when an incorrect argument is passed to the function. In this case, the game automatically replaces it with NIL, i.e., with a logical zero. By the way, this is the reason for

SetObjectEnabled("skel", false);

I intentionally wrote in my post

SetObjectEnabled("skel", nil);

However, this usually does not lead to a critical error. If there is nothing else in the console, try checking the object's setting. You can only delete objects that have the IsRemovable property set to true.