ValidateSettings field gets wrong setting if empty/no PreValue is chosen

[inetzo]

When you add more than one fields with PreValues, the ValidateSettings methode gets the wrong setting value.
Hard to explain so here are some screenshots:

The message appears, i choos "Emailaddress". Then i add an other field of the same type and call this "Lastname" and again choose no value for ProfileField.

Reproduction

Here is an example class of the formfield:

    public class TestField : FieldType
    {
        [Setting("ProfileField", Description = "", View = "Dropdownlist", PreValues = "Name, Emailaddress, Phone")]
        public string ProfileField { get; set; }

        public TestField(IScopeProvider scopeProvider)
        {
            Id = new Guid("6e73befe-c39e-436f-ac45-240ed645889e");
            Name = "Testfield";
            Description = "Test";
            DataType = FieldDataType.String;
            FieldTypeViewName = "FieldType.Test.cshtml";
            Icon = "icon-user ";
            HideLabel = false;
            SupportsPreValues = false;
            SupportsRegex = false;
            SortOrder = 25;
        }

        public override List<Exception> ValidateSettings()
        {
            List<Exception> exceptions = new List<Exception>();

            if (string.IsNullOrEmpty(this.ProfileField))
                exceptions.Add(new Exception("Choose a value"));
            return exceptions;

        }

    }

Expected result

I would expect that the setting value of ProfileField == null when no PreValue is chosen.

Actual result

The prevalue of the first set field is passed

[AndyButland]

Thanks - I've been able to replicate, and have found a fix, so will include in the next release.