Managed exception marshaling interferes with the debugger, because it adds
exception handlers to executing code, which makes the Mono runtime think an
exception is handled when logically it's not (although technically it is).
The consequence is that the IDEs will only be notified when we re-throw the
exception after catching it, making it impossible for the IDEs to stop when
the exception is thrown (they will instead stop when we re-throw the
exception).
So disable managed exception marshaling (unless the user changed the default
behavior) when a debugger is attached.
This is the same behavior as Xamarin.Android.
https://bugzilla.xamarin.com/show_bug.cgi?id=45116
Timothy Risi
Rolf Bjarne Kvinge