### Godot version

master

### System information

Godot v4.2.beta (0ea75d77c) - Windows 10.0.22621 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2070 (NVIDIA; 31.0.15.3598) - Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz (12 Threads)

### Issue description

When any of the Import, Filesystem, Node, or History docks are floating, changing an editor feature crashes the engine.
Changing any setting or selecting a different profile triggers it.

This is because `EditorNode::_feature_profile_changed` assumes the docks are in a `TabContainer`, and if they are floating they aren't in one.


### Steps to reproduce

Make any of these docks floating: Import, Filesystem, Node, or History
Open Editor Features (Editor -> Manage Editor Features...)
Make a profile (if you have none) or change a setting on the existing profile

### Minimal reproduction project

n/a
for (int i = 0; i < p_node->get_child_count(); i++) {
		AnimationMixer *mixer = Object::cast_to<AnimationMixer>(p_node->get_child(i));
		if (mixer && mixer->is_reset_on_save_enabled() && mixer->can_apply_reset()) {
			Ref<AnimatedValuesBackup> backup = mixer->apply_reset();
			if (backup.is_valid()) {
				Pair<AnimationMixer *, Ref<AnimatedValuesBackup>> pair;
				pair.first = mixer;
				pair.second = backup;
				r_anim_backups->push_back(pair);
			}
		}
		_reset_animation_mixers(p_node->get_child(i), r_anim_backups);
	}
}
void EditorNode::_save_scene(String p_file, int idx) {
	if (!saving_scene.is_empty() && saving_scene == p_file) {
		return;
	}
	Node *scene = editor_data.get_edited_scene_root(idx);
	if (!scene) {
		show_accept(TTR("This operation can't be done without a tree root."), TTR("OK"));
		return;
	}
	if (!scene->get_scene_file_path().is_empty() && _validate_scene_recursive(scene->get_scene_file_path(), scene)) {
		show_accept(TTR("This scene can't be saved because there is a cyclic instance inclusion.\nPlease resolve it and then attempt to save again."), TTR("OK"));
		return;
	}
	scene->propagate_notification(NOTIFICATION_EDITOR_PRE_SAVE);
	editor_data.apply_changes_in_editors();
	List<Pair<AnimationMixer *, Ref<AnimatedValuesBackup>>> anim_backups;