Reproducible crash on v2.07 when selecting to not continue after an unsupported game is added

[nm3210]

I have downloaded and am running with the v2.07 zipped exe.

When trying to add a game ('Solitaire (U).nes' in this case) with unsupported mappers I get the following message:

"Sorry, Solitaire (U).nes uses mapper #79 but this mapper is not supported by NES Mini and game probably will not start. Do you want to add this game anyway?".

Then, when selecting NO the program crashes with the following exception text:

System.NullReferenceException: Object reference not set to an instance of an object.
   at com.clusterrr.hakchi_gui.MainForm.buttonAddGames_Click(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

[ClusterM]

Will be fixed in new version. Thanks!