Notice, that you are trying to use WinForms control in WPF project. And icon class from WinForms doesn't support pack URIs.
Since you want to store your image in your assembly, you can't get it as WinForms Icon easily. WPF usually works with ImageSource class and you can convert it to WF icon (How can I convert BitmapImage to Icon?), but I would call it pain.
NotifyIcon is not implemented in WPF, so I suggest to try this solution.
More detais: Can I use NotifyIcon in WPF?