How to get icon texture for Player's Backpack

Guides UI and Macro
1

I have been unable to get the icon texture for the player’s backpack (in bag slot 0). Evidently, the player’s backpack is treated differently than the other bags (in slots 1 - 4). I’ve tried GetItemInfo() and GetItemIcon(), both of which work perfectly for bags in slots, 1 - 4. In the snippet below the bagName is “Backpack”, returned by GetBagName(0):

		local name, _,_,_,_,_,_,_,_,iconTexture = GetItemInfo( bagName )	
		print( name, iconTexture )	-- returns nil, nil

		local iconFileId = GetItemIcon( bagName )
		print( iconFileId )			-- returns nil

I’ve also had no luck is searching through the repository of icons on Wowhead, etc.

Pretty sure I’ve missed something obvious.

2 
MainMenuBarBackpackButton:GetSlotAtlases()

Which just returns bag-main which is the texture atlas that you could use with SetAtlas.

frame.texture:SetAtlas("bag-main")

There are seperate GetSlotAtlases() functions for the Reagent bag and non-backpack bags. All return atlasses for normal, no-bag-in-slot and highlight textures.