WowAce

What exactly is wrong?

 Deselecting all filter options in pet scan generates lua error.

What version of the product are you using?

See: https://wow.gamepedia.com/API_Frame_SetBackdrop

This is no longer a part of the World of Warcraft API. The backdrop API has been moved to BackdropTemplateMixin It was removed in patch 9.0.1.

If you get an error, please paste the ENTIRE thing here: 

Message: ...s\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua:894: attempt to call method 'SetBackdrop' (a nil value)
Time: Thu Jan 21 22:40:33 2021
Count: 3
Stack: ...s\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua:894: attempt to call method 'SetBackdrop' (a nil value)
[string "@Interface\AddOns\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua"]:894: in function `Reset'
[string "@Interface\AddOns\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua"]:579: in function <...s\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua:553>
[string "@Interface\AddOns\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua"]:819: in function `Spawn'
[string "@Interface\AddOns\Collectinator\Interface\List.lua"]:887: in function `Update'
[string "@Interface\AddOns\Collectinator\Interface\FilterMenus.lua"]:62: in function <...rface\AddOns\Collectinator\Interface\FilterMenus.lua:57>

Locals: self = LibDialog-1.0_Dialog1 {
0 = <userdata>
is_new = true
text = <unnamed> {
}
close_button = <unnamed> {
}
}
(*temporary) = nil
(*temporary) = LibDialog-1.0_Dialog1 {
0 = <userdata>
is_new = true
text = <unnamed> {
}
close_button = <unnamed> {
}
}
(*temporary) = <table> {
bgFile = "Interface\DialogFrame\UI-DialogBox-Background"
tileSize = 32
edgeFile = "Interface\DialogFrame\UI-DialogBox-Border"
tile = true
edgeSize = 32
insets = <table> {
}
}
(*temporary) = "attempt to call method 'SetBackdrop' (a nil value)"
DEFAULT_DIALOG_WIDTH = 320
DEFAULT_DIALOG_HEIGHT = 72
DEFAULT_DIALOG_BACKDROP = <table> {
bgFile = "Interface\DialogFrame\UI-DialogBox-Background"
tileSize = 32
edgeFile = "Interface\DialogFrame\UI-DialogBox-Border"
tile = true
edgeSize = 32
insets = <table> {
}
}
_Dialog_OnShow = <function> defined @Interface\AddOns\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua:229
_Dialog_OnHide = <function> defined @Interface\AddOns\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua:243
_Dialog_OnUpdate = <function> defined @Interface\AddOns\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua:264
_Dialog_OnEvent = <function> defined @Interface\AddOns\Collectinator\libs\LibDialog-1.0\LibDialog-1.0.lua:287