From f1587c8a7dcb6e28ee6659b83b02a4c6d3bd4073 Mon Sep 17 00:00:00 2001
From: PouleyKetchoupp <pouleyketchoup@gmail.com>
Date: Fri, 18 Jun 2021 10:54:09 -0700
Subject: [PATCH] Fix export var override in PackedScene at runtime

Regression fix: update_exports is tool only and should be used only in
the editor, otherwise it can cause export variable overrides from
instances to be discarded in favor of the parent's value.
---
 scene/resources/packed_scene.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scene/resources/packed_scene.cpp b/scene/resources/packed_scene.cpp
index ab8a4b79349..9f04ff80e1c 100644
--- a/scene/resources/packed_scene.cpp
+++ b/scene/resources/packed_scene.cpp
@@ -471,7 +471,9 @@ Error SceneState::_parse_node(Node *p_owner, Node *p_node, int p_parent_idx, Map
 	StringName type = p_node->get_class();
 
 	Ref<Script> script = p_node->get_script();
-	if (script.is_valid()) {
+	if (Engine::get_singleton()->is_editor_hint() && script.is_valid()) {
+		// Should be called in the editor only and not at runtime,
+		// otherwise it can cause problems because of missing instance state support.
 		script->update_exports();
 	}