check if player is null when updating card menu (#4346)

cockatrice/src/tab_game.cpp

@@ -1412,12 +1412,15 @@ Player *TabGame::getActiveLocalPlayer() const
 
 void TabGame::updateCardMenu(AbstractCardItem *card)
 {
-    Player *p;
-    if ((clients.size() > 1) || !players.contains(localPlayerId))
-        p = card->getOwner();
-    else
-        p = players.value(localPlayerId);
-    p->updateCardMenu(static_cast<CardItem *>(card));
+    Player *player;
+    if ((clients.size() > 1) || !players.contains(localPlayerId)) {
+        player = card->getOwner();
+    } else {
+        player = players.value(localPlayerId);
+    }
+    if (player != nullptr) {
+        player->updateCardMenu(static_cast<CardItem *>(card));
+    }
 }
 
 void TabGame::createMenuItems()