Fix mulligan with zero cards

forge-game/src/main/java/forge/game/card/CardFactory.java

@@ -116,7 +116,6 @@ public class CardFactory {
         //out.setFaceDown(in.isFaceDown());
 
         return out;
-
     }
 
     /**
@@ -740,7 +739,6 @@ public class CardFactory {
                 }
             }
 
-
             if (sa.hasParam("GainThisAbility") && (sa instanceof SpellAbility)) {
                 SpellAbility root = ((SpellAbility) sa).getRootAbility();
 

forge-game/src/main/java/forge/game/mulligan/AbstractMulligan.java

@@ -29,6 +29,7 @@ public abstract class AbstractMulligan {
 
     public void mulligan() {
         CardCollection toMulligan = new CardCollection(player.getCardsIn(ZoneType.Hand));
+        if (toMulligan.isEmpty()) return;
         revealPreMulligan(toMulligan);
         for (final Card c : toMulligan) {
             player.getGame().getAction().moveToLibrary(c, null);