[.NET 7.0.1] InvalidCastException in ErrorProvider

.NET version

7.0.1

Did it work in .NET Framework?

Yes

Did it work in any of the earlier releases of .NET Core or .NET 5+?

No response

Issue description

System.InvalidCastException exception is thrown in ErrorProvider.

Steps to reproduce

1. Create a .NET 7.0 WinForm app.
2. Replace Form1.cs with the following code
3. Launch the app.

namespace WinFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            var model = new MyModel();
            this.DataBindings.Add("Text", model, "Error");
            new ErrorProvider(this).DataSource = model; // InvalidCastException !!!
        }
    }

    public class MyModel : System.ComponentModel.IDataErrorInfo
    {
        public string this[string columnName] => "";
        public string Error => "";
    }
}

Excepted Result: No exception thrown.

Actual Result: This exception is thrown in code:

System.InvalidCastException HResult=0x80004002 Message=Unable to cast object of type ‘System.Collections.Generic.KeyValuePair`2[System.Windows.Forms.Control,System.String]’ to type ‘System.Collections.DictionaryEntry’. Source=System.Windows.Forms Stack Trace: at System.Windows.Forms.ErrorProvider.ErrorManager_CurrentChanged(Object sender, EventArgs e) at System.Windows.Forms.ErrorProvider.SetErrorManager(Object newDataSource, String newDataMember, Boolean force) at WinFormsApp1.Form1…ctor() (Form1.cs):line 13 at WinFormsApp1.Program.Main() (Program.cs):line 14

Other information https://github.com/dotnet/winforms/pull/7037

// Hashtable controlError = new Hashtable(bindingsCount);
Dictionary<Control, string> controlError = new(bindingsCount);
...
IEnumerator enumerator = controlError.GetEnumerator();
while (enumerator.MoveNext())
{
    DictionaryEntry entry = (DictionaryEntry)enumerator.Current; // Invalid Cast !!!
    SetError((Control)entry.Key, (string?)entry.Value);
}

[gpetrou]

Sorry, I should have checked that part of the code when I changed it. I added a small PR with a fix.

[Ashley-Li]

Verified with .NET 8 Preview 1 TP build: .NET 8.0.100-preview.1.23108.10, issue was fixed as same as above test result.