File PrusaSlicer-2.9.0-pr13885-printconfig-segfault.patch of Package PrusaSlicer

From aaa7ab6ca2b593a4f20a08292a6fb44339029474 Mon Sep 17 00:00:00 2001
From: Ryan Heule <rmheule@yahoo.com>
Date: Wed, 1 Jan 2025 16:36:04 -0600
Subject: [PATCH] Avoid null pointer dereference for partial configuration
 settings

---
 src/libslic3r/PrintConfig.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 907fdfb02a..efa9be9760 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -5130,7 +5130,14 @@ void DynamicPrintConfig::normalize_fdm()
         }
     }
 
-    if (this->has("wipe_tower_extruder")) {
+    // This method is called repeatedly while building configuration.  We may
+    // not have enough info yet to determine whether the extruder is valid;
+    // wait until we do before checking.
+    //
+    // NOTE:  other extruder validation (e.g. perimeter_extruder, infill_extruder)
+    // happens elsewhere, as those settings can be modified for specific print
+    // objects or sometimes even regions of objects.
+    if (this->has("wipe_tower_extruder") && this->has("nozzle_diameter")) {
         // If invalid, replace with 0.
         int extruder = this->opt<ConfigOptionInt>("wipe_tower_extruder")->value;
         int num_extruders = this->opt<ConfigOptionFloats>("nozzle_diameter")->size();