WowAce

Getting this error every once in a while, only since I recently started doing pet battles.

12x FrameXML\PetActionBarFrame.lua:246: attempt to perform arithmetic on a nil value
FrameXML\PetActionBarFrame.lua:246: in function `PetActionBar_UpdatePositionValues'
FrameXML\UIParent.lua:3060: in function `UIParentManageFramePositions'
FrameXML\UIParent.lua:2374: in function <FrameXML\UIParent.lua:2361>
[C]: in function `SetAttribute'
FrameXML\UIParent.lua:3170: in function <FrameXML\UIParent.lua:3168>
[C]: ?
[C]: in function `UIParent_ManageFramePositions'
FrameXML\MainMenuBar.lua:172: in function <FrameXML\MainMenuBar.lua:149>
[C]: in function `MainMenuBarVehicleLeaveButton_Update'
FrameXML\MainMenuBar.lua:146: in function <FrameXML\MainMenuBar.lua:145>

Locals:
(*temporary) = nil
(*temporary) = MainMenuBarVehicleLeaveButton {
0 = <userdata>
Highlight = <unnamed> {
}
ClearSetPoint = <function> defined @Bartender4\Bar.lua:547
}
(*temporary) = "attempt to perform arithmetic on a nil value"

The error is from t he default UI, not Bartender. very weird!