Fix Godot 4.7 typed array crash: add freed-object filtering in PropertyPool and PerObjectHistory

scripts/headless_server.gd

@@ -110,7 +110,14 @@ func _on_first_peer_join(_peer_id: int) -> void:
 		return
 	_first_client_connected = true
 
-	print("[HeadlessServer] First client connected — starting netfox tick loop...")
+	print("[HeadlessServer] First client connected — letting avatar spawn...")
+
+	# Wait TWO frames so PlayerSpawner._handle_new_peer() creates the avatar
+	# BEFORE NetworkTime starts. The tick loop needs at least one subject.
+	await get_tree().process_frame
+	await get_tree().process_frame
+
+	print("[HeadlessServer] Starting netfox tick loop with player subjects...")
 
 	# Start netfox tick loop now that we have at least one player
 	if NetworkTime and NetworkTime.has_method("start"):