unity-lens-video fails to build from source (using deprecated vala)

Making all in src
make[3]: Entering directory '/home/packages/tmp/x/unity-lens-video-0.3.15+13.10.20130920/src'
/usr/bin/valac -C --pkg dee-1.0 --pkg unity --pkg unity-extras --pkg gio-2.0 --pkg gio-unix-2.0 --pkg glib-2.0 --pkg gee-0.8 --pkg zeitgeist-1.0 --vapidir . --vapidir ../vapi --target-glib=2.26 blacklist-tracker.vala daemon.vala main.vala locate.vala scope.vala config.vala thumbnailer.vala utils.vala video-file.vala
blacklist-tracker.vala:70.37-70.68: warning: unhandled error `GLib.Error'
      Variant all_templates = yield blacklist_proxy.get_templates ();
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
blacklist-tracker.vala:51.7-51.30: warning: implicit .begin is deprecated
blacklist-tracker.vala:57.11-57.26: warning: implicit .begin is deprecated
scope.vala:156.29-156.57: error: Argument 1: Cannot convert from `GLib.CompareFunc?' to `GLib.CompareDataFunc<Unity.VideoLens.VideoFile?>?'
          result_list.sort ((GLib.CompareFunc?)sort_alpha);
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
scope.vala:200.27-200.34: warning: GLib.PtrArray has been deprecated since vala-0.26. Use GenericArray
scope.vala:127.15-127.21: warning: implicit .begin is deprecated
scope.vala:76.9-76.23: warning: implicit .begin is deprecated
scope.vala:293.9-293.35: warning: implicit .begin is deprecated
daemon.vala:31.9-31.23: warning: unhandled error `GLib.Error'
        scope.export ();
        ^^^^^^^^^^^^^^^
Compilation failed: 1 error(s), 8 warning(s)
Makefile:1063: recipe for target 'unity_video_lens_daemon.vala.stamp' failed
make[3]: *** [unity_video_lens_daemon.vala.stamp] Error 1
make[3]: Leaving directory '/home/packages/tmp/x/unity-lens-video-0.3.15+13.10.20130920/src'
Makefile:451: recipe for target 'all-recursive' failed
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory '/home/packages/tmp/x/unity-lens-video-0.3.15+13.10.20130920'
Makefile:382: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory '/home/packages/tmp/x/unity-lens-video-0.3.15+13.10.20130920'
dh_auto_build: make -j1 returned exit code 2
debian/rules:5: recipe for target 'build' failed
make: *** [build] Error 2