System.NullReferenceException: 'Object reference not set to an instance of an object.' Guna.UI2.WinForms.Guna2Button.CheckedState.get returned null.

Question

namespace WindowsFormsApp2
{
    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// true if managed resources should be disposed; otherwise, false.
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.guna2Button1 = new Guna.UI2.WinForms.Guna2Button();
            this.SuspendLayout();
            // 
            // guna2Button1
            // 
            this.guna2Button1.CheckedState.Parent = this.guna2Button1;
            this.guna2Button1.CustomImages.Parent = this.guna2Button1;
            this.guna2Button1.Font = new System.Drawing.Font("Segoe UI", 9F);
            this.guna2Button1.ForeColor = System.Drawing.Color.White;
            this.guna2Button1.HoverState.Parent = this.guna2Button1;
            this.guna2Button1.Location = new System.Drawing.Point(538, 329);
            this.guna2Button1.Name = "guna2Button1";
            this.guna2Button1.ShadowDecoration.Parent = this.guna2Button1;
            this.guna2Button1.Size = new System.Drawing.Size(180, 45);
            this.guna2Button1.TabIndex = 0;
            this.guna2Button1.Text = "guna2Button1";
            this.guna2Button1.Click += new System.EventHandler(this.guna2Button1_Click);
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 16F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(800, 450);
            this.Controls.Add(this.guna2Button1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);

        }

        #endregion

        private Guna.UI2.WinForms.Guna2Button guna2Button1;
    }
}

and this the form1.cs code

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; using Guna.UI2.WinForms;  namespace WindowsFormsApp2 {     public partial class Form1 : Form     {         public Form1()         {             InitializeComponent();         }          private void guna2Button1_Click(object sender, EventArgs e)         {             MessageBox.Show("Hello world");         }     } }