Exceptions are treated differently depending on where they occur in GJS

gistfile1.js

const Gtk = imports.gi.Gtk;
Gtk.init(null);

let w = new Gtk.Window();
let b = new Gtk.Button({ label: "Click me for an exception" });
w.add(b);

b.connect('clicked', function() {
    throw("This exception is not caught, only printed");
});
w.connect('destroy', Gtk.main_quit);

w.show_all();
try {
    Gtk.main();
    throw("This exception is caught");
} catch(e) {
    print("The exception I caught was this:", e);
}