I’m having an issue about adding partial class in WFA.

here’s my code

namespace test22
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        
    }

    public partial class Form1
    {

    }
}

whenever I add partial class, Form1.cs[design] pops up error

Any solutions might help. Thanks for reading my question.

removing second partial class solves error, but I want to add partial class