Guild Wars 2

Why does the level 12 Guild Hall Upgrade “Scribing: Hardened Gates” require the level 22 Guild Hall Upgrade “WvW Guild Claiming: Keeps”?

How can the prerequisite for something depend on something else that requires a higher level? This looks like a mistake to me; I think either “WvW Guild Claiming: Keeps” should be level 12 (or lower) or “Scribing: Hardened Gates” should be level 22 (or higher).