From 7bcd5113151f6e4cb053d76f90362363dc65fd3a Mon Sep 17 00:00:00 2001
From: David Capello <david@igarastudio.com>
Date: Tue, 1 Jun 2021 10:11:24 -0300
Subject: [PATCH] Fix crash on debug when painting on removed tiles after
 resizing the tileset

---
 src/app/util/cel_ops.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/app/util/cel_ops.cpp b/src/app/util/cel_ops.cpp
index 3a3f8d1fb..486f83f0d 100644
--- a/src/app/util/cel_ops.cpp
+++ b/src/app/util/cel_ops.cpp
@@ -783,7 +783,11 @@ static void remove_unused_tiles_from_tileset(
         const doc::tile_index ti = doc::tile_geti(t);
         n = std::max<int>(n, ti+1);
 #ifdef _DEBUG
-        ++tilesHistogram2[ti];
+        // This check is necessary in case the tilemap has a reference
+        // to a tile outside the valid range (e.g. when we resize the
+        // tileset deleting tiles that will not be present anymore)
+        if (ti >= 0 && ti < tilesHistogram2.size())
+          ++tilesHistogram2[ti];
 #endif
       }
     });