Blazor: InputBase.TryParseValueFromString should allow null values alias InputSelect null option

[Liero]

Scenario:

I want to let user to choose "empty" option from an InputSelect, which is represented by null value

string? SelectedItem { get; set; }
string[] Items { get; } = new [] { "Item1", "Item2", ... };

I have a project with Enable

Attempt

I've tried to create custom component derived from SelectInput that would parse empty string as null:

<InputSelectNullable @bind-Value="SelectedItem" class="form-control">
    <option></option>
    @foreach (var item in Items)
    {
        <option value="@item">@item</option>
    }
</InputSelectNullable>

/// <summary>
/// threats empty string as default(TValue).
/// E.g if TValue is a string or a class, it returns null;
/// </summary>
public class InputSelectNullable<TValue> : InputSelect<TValue> where TValue : class
{
    protected override bool TryParseValueFromString(
        string? value, 
        out TValue result, 
        out string validationErrorMessage)
    {
        if (string.IsNullOrEmpty(value))
        {
            validationErrorMessage = "";
            result = default(TValue);
            return true;
        }
        return base.TryParseValueFromString(value, out result!, out validationErrorMessage!);
    }

    protected override string? FormatValueAsString(TValue? value)
    {
        if (value == null)
        {
            return string.Empty;
        }
        return base.FormatValueAsString(value);
    }
}

However, I'm getting warning CS8601: Possible null reference assignment:

It's because the base method is marked with [MaybeNullWhen(false)] attribute:

protected abstract bool TryParseValueFromString(
    string? value, 
    [MaybeNullWhen(false)] out TValue result, 
    [NotNullWhen(false)] out string? validationErrorMessage);