I've not yet had time to look deeper into this but here its a userdata value
Code:
1x FrameXML\UIDropDownMenu.lua:1016: attempt to concatenate global "UIDROPDOWNMENU_MENU_LEVEL" (a userdata value)
FrameXML\UIDropDownMenu.lua:1016: in function "UIDropDownMenu_ClearAll"
FrameXML\WorldMapFrame.lua:893: in function "WorldMapLevelDropDown_Update"
FrameXML\WorldMapFrame.lua:1930: in function "WorldMapFrame_UpdateMap"
FrameXML\WorldMapFrame.lua:245: in function <FrameXML\WorldMapFrame.lua:231>
<in C code>
FrameXML\WorldMapFrame.lua:1082: in function "WorldMapButton_OnClick"
FrameXML\WorldMapFrame.lua:768: in function <FrameXML\WorldMapFrame.lua:761>
Locals: