Comment 2 for bug 1428711

StacktraceTop:
 g_variant_is_trusted (value=value@entry=0x0) at /build/buildd/glib2.0-2.43.91/./glib/gvariant-core.c:607
 g_variant_builder_add_value (builder=builder@entry=0x7fff1b3f2310, value=0x0) at /build/buildd/glib2.0-2.43.91/./glib/gvariant.c:3432
 accounts_service_sound_settings_dbus_proxy_set_state (self=0x1358ad0, value=0x0) at /build/buildd/indicator-sound-12.10.2+15.04.20150227.1/obj-x86_64-linux-gnu/src/accounts-service-sound-settings.c:503
 accounts_service_user_set_player (self=0x12a6ec0, value=value@entry=0x13248f0) at /build/buildd/indicator-sound-12.10.2+15.04.20150227.1/obj-x86_64-linux-gnu/src/accounts-service-user.c:962
 indicator_sound_service_update_player_actions (self=0x12c8970) at /build/buildd/indicator-sound-12.10.2+15.04.20150227.1/obj-x86_64-linux-gnu/src/service.c:2399