Error node_to_set.position when switch scenes

[juliusspeak]

Cogito and Godot Engine Version:
cogito beta, godot 4.3.1.rc

Description:
When switching scenes, an error occurs while loading cogito_vehicle, and sometimes while loading other objects. If you ignore the error and continue (F12), the object will still be in the correct place.

Screenshots:

[juliusspeak]

It seems that this error is caused by the fact that I had added
self.add_to_group("Persist") in cogito_vehicle.

[juliusspeak]

I get an error related to the garbage truck (cogito_vehicle) when loading from the scene Building0Room1 to Building0Room0. These scenes don’t have the garbage truck; it’s in a completely different scene, but for some reason, it still tries to load here.

[Phazorknight]

This is probably fixable but depends a bit on what behaviour you're aiming for.

First, undo adding cogito_vehicle to the "persist" group, as it inherits from cogito_sittable which is already in a saving-related group ("save_object_state")

It's probably helpful to fully understand how these two groups work within Cogito's save system, and this will help you add the desired behaviour:

"Persist" group is used for objects that can be removed from scenes (stuff like items, enemies, destructables)
When Cogito loads a scene that has a temporary save state, it actually deletes all the "Persist" objects from the cogito_scene first, then adds them back in based on the data in the scene_state.
This requires that each object has valid state_data (and missing state_data is what seems to be causing your error)

"save_object_state" group on the other hand is used for objects that are always present within a cogito_scene (like doors, switches, etc). When Cogito loads a scene, it overwrites any objects data in this group with the saved state_data (so for example if a door was left open, a switch was left on/off etc).
This can also include basic information like position/rotation etc.

If you need specific custom behaviour for your object's state that's derived from the cogito_sittable or the cogito_vehicle, I'd probably overriding what state_data is saved to fit your needs, by overriding the save() function.

state_data is a dictionary, so it's very easy to add custom values that will get saved/loaded.
As a reference, this is the default save() function for sittables (which is also used by vehicles)

[juliusspeak]

It seems there is no problem