bug: enemie movement sometimes deref nullptr when calling get_pos()

fixed level gen

src/enemies.cc

@@ -79,6 +79,10 @@ void new_enemy(RNG *rng, std::unique_ptr<enemy_base> &p,
                 p = make_unique<merchant>(rng, enabled_features, pos, which_room);
                 break;
 
+        case rhalfling:
+                p = make_unique<halfling>(rng, enabled_features, pos, which_room);
+                break;
+
         default:
                 break;
         }

src/input/file_input.cc

@@ -31,7 +31,7 @@ game_command file_input::get_command() {
 
                 return (game_command)((tmp = get_direction(cmd)) ==
                                       game_command_panic
-                                      ? tmp : tmp - move_north +
+                                      ? tmp : tmp +
                                       (use ? apply_north : attack_north));
         } else if (cmd == "yes") {
                 return game_command::enter;

src/player.cc

@@ -122,7 +122,7 @@ long_result player_base::interpret_command(level *lvl, game_command cmd) {
                                                lvl->get_elist());
                 auto res = attack((character *)tmp);
 
-                if (tmp->is_dead())
+                if (tmp != nullptr && tmp->is_dead())
                         tmp->dies(lvl, this);
 
                 return res;