Currently levelling Classic Blacksmithing on a new realm in Retail for the re-introduced Naxx patterns. First craft of a new item gives me an error.
For example, when crafting Green Iron Leggings, on the first craft. Blacksmithing is filtered to "Classic" and "Has Skill Up".

32x ...faceCraftSim/Modules/CraftResults/Frames.lua:185: attempt to compare number with nil
[string "@CraftSim/Modules/CraftResults/Frames.lua"]:185: in function compFunc' [string "@CraftSim/Libs/GUTIL-1.0/GUTIL.lua"]:393: in function Sort'
[string "@CraftSim/Modules/CraftResults/Frames.lua"]:184: in function UpdateItemList' [string "@CraftSim/Modules/CraftResults/CraftResults.lua"]:110: in function AddCraftData'
[string "@CraftSim/Modules/CraftResults/CraftResults.lua"]:165: in function AddResult' [string "@CraftSim/Modules/CraftResults/CraftResults.lua"]:225: in function callback'
[string "@CraftSim/Libs/GUTIL-1.0/GUTIL.lua"]:332: in function ContinueOnAllItemsLoaded' [string "@CraftSim/Modules/CraftResults/CraftResults.lua"]:224: in function processCraftResults'
[string "@CraftSim/Modules/CraftResults/CraftResults.lua"]:42: in function <...ddOns/CraftSim/Modules/CraftResults/CraftResults.lua:41>

Locals:
a =

{
qualityID = 5
quantity = 1
item = {
}
quantityMulticraft = 0
}
b = {
quantity = 1
item = {
}
quantityMulticraft = 0
}
(*temporary) = nil
(*temporary) = 1
(*temporary) = {
GetItemLocation = defined @FrameXML/ObjectAPI/Item.lua:104
IsDataEvictable = defined @FrameXML/ObjectAPI/Item.lua:306
LockItem = defined @FrameXML/ObjectAPI/Item.lua:175
IsItemDataCached = defined @FrameXML/ObjectAPI/Item.lua:295
GetInventoryTypeName = defined @FrameXML/ObjectAPI/Item.lua:289
GetItemQualityColor = defined @FrameXML/ObjectAPI/Item.lua:252
Matches = defined @FrameXML/ObjectAPI/Item.lua:66
itemLink = "|cffffffff|Hitem:118721::::::::70:253:::::::::|h[Secret of Draenor Leatherworking]|h|r"
GetItemQuality = defined @FrameXML/ObjectAPI/Item.lua:223
Clear = defined @FrameXML/ObjectAPI/Item.lua:131
GetItemIcon = defined @FrameXML/ObjectAPI/Item.lua:187
GetItemMaxStackSize = defined @FrameXML/ObjectAPI/Item.lua:262
ContinueWithCancelOnItemLoad = defined @FrameXML/ObjectAPI/Item.lua:334
IsItemLocked = defined @FrameXML/ObjectAPI/Item.lua:171
IsRecordDataCached = defined @FrameXML/ObjectAPI/Item.lua:344
IsItemEmpty = defined @FrameXML/ObjectAPI/Item.lua:138
SetItemID = defined @FrameXML/ObjectAPI/Item.lua:94
IsStackable = defined @FrameXML/ObjectAPI/Item.lua:273
SetItemLink = defined @FrameXML/ObjectAPI/Item.lua:89
GetInventoryType = defined @FrameXML/ObjectAPI/Item.lua:278
SetItemGUID = defined @FrameXML/ObjectAPI/Item.lua:99
GetItemID = defined @FrameXML/ObjectAPI/Item.lua:160
GetCurrentItemLevel = defined @FrameXML/ObjectAPI/Item.lua:241
GetItemQualityColorRGB = defined @FrameXML/ObjectAPI/Item.lua:257
UnlockItem = defined @FrameXML/ObjectAPI/Item.lua:181
GetItemGUID = defined @FrameXML/ObjectAPI/Item.lua:115
SetItemLocation = defined @FrameXML/ObjectAPI/Item.lua:84
GetItemName = defined @FrameXML/ObjectAPI/Item.lua:197
IsItemInPlayersControl = defined @FrameXML/ObjectAPI/Item.lua:150
GetItemLink = defined @FrameXML/ObjectAPI/Item.lua:208
ValidateForContinueOnItemLoad = defined @FrameXML/ObjectAPI/Item.lua:311
GetStaticBackingItem = defined @FrameXML/ObjectAPI/Item.lua:146
HasItemLocation = defined @FrameXML/ObjectAPI/Item.lua:127
ContinueWithCancelOnRecordLoad = defined @FrameXML/ObjectAPI/Item.lua:340
ContinueOnItemLoad = defined @FrameXML/ObjectAPI/Item.lua:328
GetStackCount = defined @FrameXML/ObjectAPI/Item.lua:234
}
(*temporary) = "attempt to compare number with nil"