- Only create a BYE pairing if there's an assigned Bye Player

forge-gui/src/main/java/forge/tournament/system/TournamentSwiss.java

@@ -54,11 +54,14 @@ public class TournamentSwiss extends AbstractTournament {
         List<TournamentPlayer> leftoverPlayers = new ArrayList<>();
 
         List<TournamentPlayer> groupPlayers = Lists.newArrayList(allPlayers);
+
+        if (byePlayer != null) {
             groupPlayers.remove(byePlayer);
 
             TournamentPairing byePair = new TournamentPairing(activeRound, Lists.<TournamentPlayer>newArrayList(byePlayer));
             byePair.setBye(true);
             activePairings.add(byePair);
+        }
 
         if (groupPlayers.isEmpty()) {
             return;