export during runtime not working

[klauskobald]

I am trying to export like so:

        ExporterSettings.Export.folder = "/Users/klausk/Downloads/sein/";
        ExporterSettings.Export.clear = true;
        ExporterSettings.Export.name = "test";
        var e=new Exporter();
        e.Export();

but I get an error:

KeyNotFoundException: The given key was not present in the dictionary.
System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) (at <695d1cc93cca45069c528c15c9fdd749>:0)
SeinJS.ExtensionManager.GetExtensionName (System.Type FactoryClass) (at Assets/SeinJSUnityToolkit/Extensions/Basic/ExtensionManager.cs:100)

in this line of EditorExport.ExportOne:
ExtensionManager.Serialize(ExtensionManager.GetExtensionName(typeof(Sein_rendererExtensionFactory)), entry, entry.root.Extensions);

any Ideas?