created_cb: don't leak error
created_cb: don't leak error

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=27727

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control