Set Apple Script App as custom browser on macOS mojave

I followed instructions here: Default Browser .plist location

But it does't work. My custom app doesn't show up in the list of browsers to choose from in system settings:

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I have tried:

calling /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister on the modified plist file.
moving the custom app to /Applications

What does it take to get this to work on macOS mojave? Thanks

Solution 1:

I eventually solved the problem using SwiftDefaultApps command line tool swda. It works. Although, this box now shows up blank in system setting.

swda is located inside the zip file of the latest release at https://github.com/Lord-Kamina/SwiftDefaultApps/releases

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