Debug append

src/migl/util/ConsListImpl.java

@@ -47,7 +47,7 @@ public class ConsListImpl<E> extends Cons<E, ConsList<E>> implements ConsList<E>
 	}
 	
 	private ConsList<E> appendRec(E e, ConsList<E> list) {
-		if(list == null) {
+		if(list == null || list.isEmpty()) {
 			return new ConsListImpl<>(e, null);
 		}
 		return new ConsListImpl<>(list.car(), this.appendRec(e, list.cdr()));