SimpleFirewall error

I was able to build and execute this for long time using Xcode 11 (betas).

Now I downloaded again, and I see a compilation error ( link time) ;; _main not found. Of course there is no main in the UI application file, not even main.swift, just that few lines in Appdelegate.swift

// https://jameshfisher.com/2017/03/18/what-is-swift-nsapplicationmain/

@NSApplicationMain

class AppDelegate: NSObject, NSApplicationDelegate {

}

It should have resolved for main, but Xcode 11.3 does not resolve, so I tried to create a main.swift in that project space with

code --

import Foundation

import AppKit

_ = NSApplicationMain(CommandLine.argc, CommandLine.unsafeArgv)

NOW IT COMPILES, AND LINKS . But I get SIGABORT. And never get the SimpleFirewall UI.

Is it the right way to resolve the -- unresolved _main ?

If so, then perhaps I can debug thru this.

Thanks