improve score return

src/main/java/fr/jaquin/bdlg/planner/controller/SolverController.java

@@ -85,6 +85,9 @@ public class SolverController {
       MealSlot casted = (MealSlot) val;
       return "{\"type\":\"MealSlot\",\"slotId\":\"" + casted.getId() + "\"}";
     }
+    if (val instanceof Integer) {
+      return val.toString();
+    }
     return "\"" + val.getClass().getName() + "\"";
   }