When I use a FieldSetting.FieldPicker on a custom fieldtype i get an exception.

[NullReferenceException: Object reference not set to an instance of an object.]
   Umbraco.Forms.Core.FieldSetting.FieldPicker.RenderControl(Setting sender, Form form) in d:\TeamCity\buildAgent\work\e4473b9ec9597356\Umbraco.Forms.Core\Common\FieldSettingType\FieldPicker.cs:34
   Umbraco.Forms.UI.Usercontrols.EditForm.RenderFieldTypeSpecificSettings(Object sender, RepeaterItemEventArgs e) in d:\TeamCity\buildAgent\work\e4473b9ec9597356\Umbraco.Forms.UI\Usercontrols\EditForm.ascx.cs:128
   System.Web.UI.WebControls.Repeater.OnItemDataBound(RepeaterItemEventArgs e) +108
   System.Web.UI.WebControls.Repeater.CreateItem(Int32 itemIndex, ListItemType itemType, Boolean dataBind, Object dataItem) +136
   System.Web.UI.WebControls.Repeater.CreateControlHierarchy(Boolean useDataSource) +443
   System.Web.UI.WebControls.Repeater.OnDataBinding(EventArgs e) +51
   System.Web.UI.WebControls.Repeater.DataBind() +75
   Umbraco.Forms.UI.Usercontrols.EditForm.RenderFieldTypeSettings(Object sender, RepeaterItemEventArgs e) in d:\TeamCity\buildAgent\work\e4473b9ec9597356\Umbraco.Forms.UI\Usercontrols\EditForm.ascx.cs:114
   System.Web.UI.WebControls.Repeater.OnItemDataBound(RepeaterItemEventArgs e) +108
   System.Web.UI.WebControls.Repeater.CreateItem(Int32 itemIndex, ListItemType itemType, Boolean dataBind, Object dataItem) +136
   System.Web.UI.WebControls.Repeater.CreateControlHierarchy(Boolean useDataSource) +443
   System.Web.UI.WebControls.Repeater.OnDataBinding(EventArgs e) +51
   System.Web.UI.WebControls.Repeater.DataBind() +75
   Umbraco.Forms.UI.Usercontrols.EditForm.Page_Load(Object sender, EventArgs e) in d:\TeamCity\buildAgent\work\e4473b9ec9597356\Umbraco.Forms.UI\Usercontrols\EditForm.ascx.cs:68
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +99
   System.Web.UI.Control.LoadRecursive() +50
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627

Is this a bug?