Godot Subnode attribute

Player.cs

class Player : KinematicBody
{
    [Subnode] private Spatial MyNode; // finds subnode called "MyNode" which is a Spatial, crash if not found
    [Subnode("custom_name")] private Label MyLabel; // finds a Label called "custom_name"
    
    public override void _Ready()
    {
        this.FindSubnodes(); // Must write `this.` because it's an extension class
    }
}

SubnodeAttribute.cs

using System;
using System.Reflection;
using Godot.Collections;

[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property)]
class SubnodeAttribute : System.Attribute
{
    public string NodePath { get; private set; }

    public SubnodeAttribute(string nodePath = null)
    {
        NodePath = nodePath;
    }
}

public static class NodeExtensions
{
    public static void FindSubnodes(this Godot.Node node)
    {
        foreach (PropertyInfo prop in node.GetType().GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
        {
            SubnodeAttribute Subnode = (SubnodeAttribute)Attribute.GetCustomAttribute(prop, typeof(SubnodeAttribute));
            if (Subnode != null)
            {
                string nodePath = Subnode.NodePath == null ? prop.Name : Subnode.NodePath;
                var subnode = node.GetNode(nodePath);
                prop.SetValue(node, subnode);
            }
        }

        foreach (FieldInfo field in node.GetType().GetFields(BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
        {
            SubnodeAttribute Subnode = (SubnodeAttribute)Attribute.GetCustomAttribute(field, typeof(SubnodeAttribute));
            if (Subnode != null)
            {
                string nodePath = Subnode.NodePath == null ? field.Name : Subnode.NodePath;
                var subnode = node.GetNode(nodePath);
                field.SetValue(node, subnode);
            }
        }
    }
}