add dbg for regenerating arena

src/logic/future_moves.rs

@@ -247,6 +247,7 @@ impl FutureMoves {
         if let Some(curr_board_idx) = curr_board {
             self.set_root_idx_raw(curr_board_idx);
         } else {
+            dbg!("regenerating arena from board");
             self.set_root_from_board(*board);
         }
     }