cat can dig again

Author: hannah-y-gao

engine/src/main/battlecode/world/RobotControllerImpl.java

@@ -983,6 +983,12 @@ private void assertCanAttackCat(MapLocation loc) throws GameActionException {
         if (!this.gameWorld.isPassable(loc)) {
             throw new GameActionException(CANT_DO_THAT, "Cats cannot attack squares with walls or dirt on them!");
         }
+        if (this.gameWorld.getRobot(loc) == null) {
+            throw new GameActionException(CANT_DO_THAT, "No robot to attack at the specified location!");
+        }
+        if (this.gameWorld.getRobot(loc) != null && this.gameWorld.getRobot(loc).getID() == this.robot.getID()) {
+            throw new GameActionException(CANT_DO_THAT, "Cannot attack self");
+        }
     }
 
     private void assertCanAttack(MapLocation loc, int cheeseConsumed) throws GameActionException {