From 29282c2a500e24e7834dcea9b4d2c9aad4aed4f5 Mon Sep 17 00:00:00 2001
From: Birk Magnussen <6238428+BMagnu@users.noreply.github.com>
Date: Sat, 13 Jun 2026 13:21:00 +0900
Subject: [PATCH 1/2] Add safeguards for invalidated model instances and
 texture replace specifically

---
 code/model/modelrender.cpp | 6 +++++-
 code/ship/ship.cpp         | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/code/model/modelrender.cpp b/code/model/modelrender.cpp
index 5743cc874e2..23bd0275851 100644
--- a/code/model/modelrender.cpp
+++ b/code/model/modelrender.cpp
@@ -3195,8 +3195,12 @@ void model_render_set_wireframe_color(const color* clr)
 
 void modelinstance_replace_active_texture(polymodel_instance* pmi, const char* old_name, const char* new_name)
 {
-	Assert(pmi != nullptr);
+	if (pmi == nullptr)
+		return;
+
 	polymodel* pm = model_get(pmi->model_num);
+	if (pm == nullptr)
+		return;
 
 	int final_index = -1;
 
diff --git a/code/ship/ship.cpp b/code/ship/ship.cpp
index 31485fc7c2d..bf8c6089f6a 100644
--- a/code/ship/ship.cpp
+++ b/code/ship/ship.cpp
@@ -8986,6 +8986,7 @@ void ship_delete( object * obj )
 	ct_ship_delete(shipp);
 	
 	model_delete_instance(shipp->model_instance_num);
+	shipp->model_instance_num = -1;
 
 	// free up any weapon model instances
 	for (int i = 0; i < shipp->weapons.num_primary_banks; ++i)

From 5d6cbab97dd763883a27a43a95ced4b2173dde09 Mon Sep 17 00:00:00 2001
From: Birk Magnussen <6238428+BMagnu@users.noreply.github.com>
Date: Sat, 13 Jun 2026 13:41:49 +0900
Subject: [PATCH 2/2] More guards

---
 code/ship/ship.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/code/ship/ship.cpp b/code/ship/ship.cpp
index bf8c6089f6a..b95c7fb01af 100644
--- a/code/ship/ship.cpp
+++ b/code/ship/ship.cpp
@@ -19698,6 +19698,9 @@ void ship_page_out_textures(int ship_index, bool release)
 
 void ship_replace_active_texture(int ship_index, const char* old_name, const char* new_name)
 {
+	if (Ships[ship_index].model_instance_num < 0)
+		return;
+	
 	polymodel_instance* pmi = model_get_instance(Ships[ship_index].model_instance_num);
 	modelinstance_replace_active_texture(pmi, old_name, new_name);
 }