add assertion: check no double-initialization

include/game_state.hpp

@@ -429,6 +429,7 @@ namespace Hanabi {
 
     template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
     void HanabiState<num_suits, num_players, hand_size>::init_backtracking_information() {
+      ASSERT(not _relative_representation.initialized);
         // Note that this function does not have to be particularly performant, we only call it once to initialize.
         const Card trash = [this]() -> Card {
             for (suit_t suit = 0; suit < num_suits; suit++) {