When trying to autostart my App after boot, I had the same Syntax errors but it looks like a visual bug because the Code was acctually working fine for me. So I ignored the red underlined things.

The problem was that I didn't activate the "Appear on top" setting for my app.

On Anrdoid, go to your apps App info -> Appear on top and set it to on

You can also program your app to direct the user to that setting, so you don't have to search for it constantly after reinstalling the app.

If you are still facing issues with autostarting the app after boot, let me know, and I can share the code.