From feb17e5acfc6eec264628db7b1531db6fc94a3e4 Mon Sep 17 00:00:00 2001
From: Daniel Monroe <github.com@danielmonroe.net>
Date: Mon, 6 Oct 2025 04:47:37 -0400
Subject: [PATCH] Make sure we don't move a nonexistent piece in SEE

added assert.

closes https://github.com/official-stockfish/Stockfish/pull/6342

No functional change
---
 src/position.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/position.cpp b/src/position.cpp
index f59632475..d0cad3e7f 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -1105,6 +1105,8 @@ bool Position::see_ge(Move m, int threshold) const {
 
     Square from = m.from_sq(), to = m.to_sq();
 
+    assert(piece_on(from) != NO_PIECE);
+
     int swap = PieceValue[piece_on(to)] - threshold;
     if (swap < 0)
         return false;