I am unsure if this is new or has been present for previous versions.

Using latest build of WoW classic and Grail/Wholly.

Present with no other add ons.

Repair Wow seems fine

Date: 2020-07-16 12:35:36
ID: 2
Error occured in: Global
Count: 4
Message: ..\AddOns\Wholly\Wholly.lua line 4134:
attempt to perform arithmetic on field 'y' (a nil value)
Debug:
Wholly\Wholly.lua:4134: ShowTooltip()
Wholly\Wholly.lua:846:
Wholly\Wholly.lua:846
Locals:
self =

Additionally, Questie maps correctly.

Are you getting this in Orgrimmar, or any other place? Do you always get this? Are you mousing over a specific pin in the map? I have tried this with both Alliance and Horde characters in Classic and am not able to reproduce it at the moment. I see the code, but it is protected to ensure there is an X value before it tries to use both the X and Y. I am wondering what data is there that has X defined but not Y. A fix can be made in code but I would love to be able to reproduce this.

Damn and double damn
Found error
Classic NPCs
G[1940]={'1421:64.60,,23.60 1421:65.80,25.20 1421:65.80,28.80 1421:67.80,25.80 1421:68.00,34.40 1421:67.40,35.60'} -- Rot Hide Plague Weaver

Double comma.
That's one of mine from a long while ago. Maybe no other user has been to Silverpine.
Sorry.
Works fine now.

Clue was when I moused down the Silverpine quest list in Wholly, that entry errored .

In Undercity, click onto Silverpine Map.

Date: 2020-07-17 14:37:24
ID: 1
Error occured in: Global
Count: 1
Message: ..\AddOns\Wholly\Wholly.lua line 851:
attempt to perform arithmetic on local 'y' (a nil value)
Debug:
Wholly\Wholly.lua:851: OnAcquired()
...ace\AddOns\Blizzard_MapCanvas\Blizzard_MapCanvas.lua:165: AcquirePin()
Wholly\Wholly.lua:830: RefreshAllData()
...ns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:76: OnMapChanged()
...ace\AddOns\Blizzard_MapCanvas\Blizzard_MapCanvas.lua:529: OnMapChanged()
...rface\AddOns\Blizzard_WorldMap\Blizzard_WorldMap.lua:115: OnMapChanged()
...ace\AddOns\Blizzard_MapCanvas\Blizzard_MapCanvas.lua:37: SetMapID()
...ace\AddOns\Blizzard_MapCanvas\Blizzard_MapCanvas.lua:731: NavigateToCursor()
...lizzard_MapCanvas\MapCanvas_ScrollContainerMixin.lua:113:
...lizzard_MapCanvas\MapCanvas_ScrollContainerMixin.lua:105
Locals:
self = {
SetNudgeSourceMagnitude = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:166
GetGlobalPosition = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:253
PanTo = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:260
owningMap = WorldMapFrame {
}
OnCanvasScaleChanged = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:270
GetNudgeSourceZoomedInMagnitude = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:175
SetScaleStyle = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:301
scaleFactor = 1
map = WorldMapFrame {
}
GetMap = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:199
OnCanvasSizeChanged = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:279
ApplyCurrentPosition = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:336
IsIgnoringGlobalPinScale = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:287
endScale = 1.200000
OnMouseEnter = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:122
pinTemplate = "WhollyPinsTemplate"
OnMouseUp = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:134
texType = "G"
OnAcquired = defined @interface\AddOns\Wholly\Wholly.lua:850
PanAndZoomTo = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:265
xcoord = 71.650000
ApplyCurrentScale = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:340
OnLoad = defined @interface\AddOns\Wholly\Wholly.lua:841
OnReleased = defined @interface\AddOns\Wholly\Wholly.lua:860
OnMapInsetMouseLeave = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:146
SetNudgeFactor = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:228
GetNudgeSourcePinZoomedOutNudgeFactor = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:207
startScale = 1
OnClick = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:118
SetNudgeZoomedInFactor = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:179
GetNudgeSourceRadius = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:162
GetNudgeTargetFactor = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:154
GetFrameLevelType = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:370
SetAlphaStyle = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:326
SetScalingLimits = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:291
SetNudgeSourceRadius = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:158
SetNudgeVector = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:216
ycoord = 29.270000
normalizedX = 0.716500
SetAlphaLimits = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:316
npcId = 14729
0 =
OnCanvasPanChanged = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:275
OnMouseLeave = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:126
SetPosition = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:240
normalizedY = 0.292700
GetPosition = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:248
SetNudgeTargetFactor = defined @interface\AddOns\Blizzard_MapCanvas\MapCanvas_DataProviderBase.lua:150
OnMo

The city/town icons are those of Eastern Kingdom and the character marker is where I am on the world map.

Hovering over a Wholly "!" gives

Date: 2020-07-17 14:43:35
ID: 2
Error occured in: Global
Count: 1
Message: ..\AddOns\Wholly\Wholly.lua line 4134:
attempt to perform arithmetic on field 'y' (a nil value)
Debug:
Wholly\Wholly.lua:4134: ShowTooltip()
Wholly\Wholly.lua:846:
Wholly\Wholly.lua:846
Locals:
self =

Then the hover over stops working

So, it's confused which map it's showing.

When I use Mapster, and try to choose Silverpine, it does nothing once the error mentioned has happened. before that error, it works fine.

The error is present with just Wholly/Grail. Fresh download, no other addons. As well as with others.

Ask further if you need to.

Alliance and Horde, two different Macs. one PC.