From 010f3adcea532420bee2382d57f9f5d4e5ad968f Mon Sep 17 00:00:00 2001
From: Agetian <stavdev@mail.ru>
Date: Sat, 20 May 2017 18:30:58 +0000
Subject: [PATCH] - Fix rare corner case crashes when an attempt is made to
 insert a card to the zone at a specific index position but that zone ends up
 being empty at that point (for instance, this can happen when clicking
 "Concede" during a mana payment for a spell). Currently this is set to issue
 a console warning for testing purposes to see if this happens in any other
 cases.

---
 forge-game/src/main/java/forge/game/zone/Zone.java | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/forge-game/src/main/java/forge/game/zone/Zone.java b/forge-game/src/main/java/forge/game/zone/Zone.java
index d6232afa8cb..a00de79a554 100644
--- a/forge-game/src/main/java/forge/game/zone/Zone.java
+++ b/forge-game/src/main/java/forge/game/zone/Zone.java
@@ -80,6 +80,13 @@ public class Zone implements java.io.Serializable, Iterable<Card> {
     }
 
     public void add(final Card c, final Integer index, final Card latestState) {
+        if (index != null && cardList.isEmpty() && index.intValue() > 0) {
+            // something went wrong, most likely the method fired when the game was in an unexpected state
+            // (e.g. conceding during the mana payment prompt)
+            System.out.println("Warning: tried to add a card to zone with a specific non-zero index, but the zone was empty! Canceling Zone#add to avoid a crash.");
+            return;
+        }
+
         // Immutable cards are usually emblems and effects
         if (!c.isImmutable()) {
             final Zone oldZone = game.getZoneOf(c);