Fix assertion

src/Lynx/Model/Move.cs

@@ -153,7 +153,9 @@ public static bool TryParseFromUCIString(ReadOnlySpan<char> UCIString, Span<Move
                         return true;
                     }
 
-                    Debug.Assert(moveList.Length == 4, "There will be 4 and always 4 moves that match sourceSquare and targetSquare when there is a promotion");
+                    Debug.Assert(moveList.Length >= 4, "There will be at least 4 moves that match sourceSquare and targetSquare when there is a promotion");
+                    Debug.Assert(moveList.ToArray().Count(m => m.PromotedPiece() != default) == 4 || moveList.ToArray().Count(m => m.PromotedPiece() != default) == 8, "There will be either 4 or 8 moves that are a promotion");
+                    Debug.Assert(moveList.ToArray().Count(m => m.SourceSquare() == sourceSquare && m.TargetSquare() == targetSquare && m.PromotedPiece() != default) == 4, "There will be 4 (and always 4) moves that match sourceSquare and targetSquare when there is a promotion");
                 }
             }
         }