Inventory Grid View is outdated and throws errors!
Please use the addon "Grid List" instead.
Or try this patched version of IGV but I won't update this so please do not ask or bother me to:
I've removed the embedded libraries and LibStub calls and made it depending on LibAddonMenu-2.0 version r28 or newer.
IGV v2.0.9.3 Baertram without LibStub and other Libs