Update ConstraintsEvalForDouble.jrag

src/main/jastadd/hanoi/ConstraintsEvalForDouble.jrag

@@ -104,7 +104,7 @@ aspect Connectives{
             //if the pillar is not empty, check if the top disk has size 1
                 return  this.getRel().getDisk(this.getRel().getNumDisk()-1).getSize();
             }else{
-                return -1.0;//no disk, the number is invalid, return -1
+                return -1;//no disk, the number is invalid, return -1
             }
     }
     eq Term2.evalDouble(){