ant@Master-Ant:~/simple-scan$ make
make  all-recursive
make[1]: Entering directory `/home/ant/simple-scan'
Making all in src
make[2]: Entering directory `/home/ant/simple-scan/src'
  VALAC  simple_scan_vala.stamp
book-view.vala:71.65-71.68: warning: Argument 2: Cannot pass null to non-null parameter type
        scroll = new Gtk.Scrollbar (Gtk.Orientation.HORIZONTAL, null);
                                                                ^^^^
ui.vala:1267.19-1267.41: error: The name `get_default' does not exist in the context of `GLib.Application'
        var app = Application.get_default () as Gtk.Application;
                  ^^^^^^^^^^^^^^^^^^^^^^^
ui.vala:1267.13-1267.63: error: var declaration not allowed with non-typed initializer
        var app = Application.get_default () as Gtk.Application;
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ui.vala:1268.9-1268.11: error: The name `app' does not exist in the context of `UserInterface.load'
        app.add_window (window);
        ^^^
simple-scan.vala:88.9-88.21: error: The name `shutdown' does not exist in the context of `Gtk.Application'
        base.shutdown ();
        ^^^^^^^^^^^^^
simple-scan.vala:86.5-86.33: error: SimpleScan.shutdown: no suitable method found to override
    public override void shutdown ()
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Compilation failed: 5 error(s), 1 warning(s)
make[2]: *** [simple_scan_vala.stamp] Error 1
make[2]: Leaving directory `/home/ant/simple-scan/src'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/ant/simple-scan'
make: *** [all] Error 2