From c8aa1de66f8d99c1f26a7430a5f2407d2c18c045 Mon Sep 17 00:00:00 2001
From: "zhimin.zeng" <zhimin.zeng@bambulab.com>
Date: Mon, 17 Mar 2025 10:27:01 +0800
Subject: [PATCH] FIX: crash when tool_change is empty

jira: none
Change-Id: Ia2d6fda6847e41054700e37a25179ae2a8d5cd46
(cherry picked from commit c38eb761c6ec5bf8013ba9f4b02ccb09985b4181)
---
 src/libslic3r/GCode/WipeTower.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/libslic3r/GCode/WipeTower.cpp b/src/libslic3r/GCode/WipeTower.cpp
index 30746cb4bc..7b41cae98a 100644
--- a/src/libslic3r/GCode/WipeTower.cpp
+++ b/src/libslic3r/GCode/WipeTower.cpp
@@ -3956,9 +3956,10 @@ void WipeTower::generate_new(std::vector<std::vector<WipeTower::ToolChangeResult
                     finish_layer_filament = block.last_nozzle_change_id;
                 }
 
-                WipeTowerBlock * last_layer_finish_block = get_block_by_category(get_filament_category(layer.tool_changes.front().old_tool), false);
-                if (!layer.tool_changes.empty() && last_layer_finish_block && last_layer_finish_block->block_id == block.block_id && finish_layer_filament == -1) {
-                    finish_layer_filament = layer.tool_changes.front().old_tool;
+                if (!layer.tool_changes.empty()) {
+                    WipeTowerBlock * last_layer_finish_block = get_block_by_category(get_filament_category(layer.tool_changes.front().old_tool), false);
+                    if (last_layer_finish_block && last_layer_finish_block->block_id == block.block_id && finish_layer_filament == -1)
+                        finish_layer_filament = layer.tool_changes.front().old_tool;
                 }
 
                 if (finish_layer_filament == -1) {