Being relatively new to Xamarin, I naively expected any errors to just show up, you know, like when you run a console app after headbutting the keyboard, it gives you some vague indication that there's a problem with your code.
My story starts with the default template of Xamarin, running just an Android application. I just want to mention again that this is the default template (admittedly I am running VS2019 and .NET Core 3.0 - at the time of writing, .NET Core 3.0 is still in preview).