### Godot version

4.0-rc6

### System information

Fedora 37, Mesa Intel ADL GT2

### Issue description

Code that works as expected at runtime fails with Nil references to (assigned) exported vars in the editor:

![tool_global_position_error](https://user-images.githubusercontent.com/364501/222031460-ffb1ecbd-5175-4a42-8470-25285ba5f821.png)


### Steps to reproduce

Try to access the `global_position` of a `Node3D` that's assigned to an exported var.

See that it works at runtime.

See that it errors in the editor with:

> Invalid get index 'global_position' (on base: 'Nil').

### Minimal reproduction project

[tool_test.zip](https://github.com/godotengine/godot/files/10856640/tool_test.zip)

ERR_FAIL_COND_V(p_scene_state.is_null(), ERR_INVALID_PARAMETER);
	clear();
	for (const StringName &E : p_scene_state->names) {
		names.append(E);
	}
	for (const Variant &E : p_scene_state->variants) {
		variants.append(E);
	}
	for (const SceneState::NodeData &E : p_scene_state->nodes) {
		nodes.append(E);
	}
	for (const SceneState::ConnectionData &E : p_scene_state->connections) {
		connections.append(E);
	}
	for (KeyValue<NodePath, int> &E : p_scene_state->node_path_cache) {
		node_path_cache.insert(E.key, E.value);
	}
	for (const NodePath &E : p_scene_state->node_paths) {
		node_paths.append(E);
	}
	for (const NodePath &E : p_scene_state->editable_instances) {
		editable_instances.append(E);
	}
	base_scene_idx = p_scene_state->base_scene_idx;
	return OK;
}
Ref<SceneState> SceneState::get_base_scene_state() const {