From Bugsack I get this error on load:

3x Interface_Wrath\FrameXML\Bindings.xml:1 Baggins/Baggins-Search.lua:1 (null)

When I try to use the addon by opening my bags, there's a recurring error:

798x Baggins/Baggins.lua:3190: attempt to call field 'IsAddOnLoaded' (a nil value)
[string "@Baggins/Baggins.lua"]:3190: in function UpdateItemButton' [string "@Baggins/Baggins.lua"]:1896: in function ReallyLayoutSection'
[string "@Baggins/Baggins.lua"]:761: in function `?'
[string "@Baggins/Baggins.lua"]:175: in function <Baggins/Baggins.lua:167>

Locals:
self =

{
cannotDetachTooltip = true
modules = {
}
CancelTimer = defined @Ace3/AceTimer-3.0/AceTimer-3.0.lua:147
CreateItemButton = defined @Baggins/Baggins.lua:2479
GetIncludeRule = defined @Baggins/Baggins-Filtering.lua:461
RemoveSection = defined @Baggins/Baggins.lua:3889
GetCachedItem = defined @Baggins/Baggins-Filtering.lua:533
OptimizeSectionLayout = defined @Baggins/Baggins.lua:1544
UpdateSectionContents = defined @Baggins/Baggins.lua:1199
IsAnyBankOpen = defined @Baggins/Baggins.lua:4165
RemoveRule = defined @Baggins/Baggins.lua:3906
OnTextUpdate = defined @Baggins/Baggins.lua:3629
InitOptions = defined @Baggins/Baggins-Options.lua:1082
ScheduleTimer = defined @Ace3/AceTimer-3.0/AceTimer-3.0.lua:94
UpdateDB = defined @Baggins/Baggins-Options.lua:1063
GetBagTypes = defined @Baggins/Baggins-Filtering.lua:89
UpdateItemButtons = defined @Baggins/Baggins.lua:2944
LayoutSection = defined @Baggins/Baggins.lua:1834
OnBankOpened = defined @Baggins/Baggins.lua:712
SetEnabledState = defined @Ace3/AceAddon-3.0/AceAddon-3.0.lua:420
Hook = defined @Ace3/AceHook-3.0/AceHook-3.0.lua:273
RegisterSkin = defined @Baggins/Baggins-Skins.lua:34
InitBagCategoryOptions = defined @Baggins/Baggins-Options.lua:3592
UpdateLayout = defined @Baggins/Baggins.lua:2933
CountNormalSlots = defined @Baggins/Baggins.lua:3717
AddCustomRule = defined @Baggins/Baggins-Filtering.lua:101
RuleTypeIterator = defined @Baggins/Baggins-Filtering.lua:123
NewModule = defined @Ace3/AceAddon-3.0/AceAddon-3.0.lua:231
MoveBag = defined @Baggins/Baggins.lua:3803
ForceFullRefresh = defined @Baggins/Baggins-Filtering.lua:429
DoRecheckCompress = defined @Baggins/Baggins-ItemOps.lua:224
GetAce3Opts = defined @Baggins/Baggins-Filtering.lua:152
GetName = defined @Ace3/AceAddon-3.0/AceAddon-3.0.lua:275
MoveRule = defined @Baggins/Baggins.lua:3838
defaultcategories = {
}
ClearSectionCaches = defined @Baggins/Baggins.lua:998
Disable = defined @Ace3/AceAddon-3.0/AceAddon-3.0.lua:310
CategoryMatchRemoved = defined @Baggins/Baggins.lua:870
Unhook = defined @Ace3/AceHook-3.0/AceHook-3.0.lua:417
CloseSpecialWindows = defined @Baggins/Baggins.lua:4199
CreateBagPlacementFrame = defined @Baggins/Baggins.lua:1952
IncludeItemInCategory = defined @Baggins/Baggins-Filtering.lua:493
Debug = defined @Baggins/Baggins.lua:118
CategoryMatchAdded = defined @Baggins/Baggins.lua:810
FireSignal = defined @Baggins/Baggins.lua:198
IsActive = defined @Baggins/Baggins.lua:393
CountAmmoSlots = defined @Baggins/Baggins.lua:3721
SlotMoved = defined @Baggins/Baggins.lua:909
SetDefaultModuleLibraries = defined @Ace3/AceAddon-3.0/AceAddon-3.0.lua:363
Baggins_CategoriesChanged = defined @Baggins/Baggins.lua:513
CloseBag = defined

The addons has become completely unusable for me.

Can confirm, I had to downgrade to version 5.0.8 and comment out lines 3-35 from Baggins-Search.lua and lines 27-29 from src/filters/ScrapAddon.lua, as all calls to IsAddOnLoaded fail - which is strange, since /run print(IsAddOnLoaded("Baggins")) works just fine.

I'm playing WoW WotLK Classic.