Instance:IsA randomly stopped working? [FIXED]

So, I'm trying to make a script that whenever somebody clicks two buttons they can insert a name to create another. I had no trouble with the script until randomly one line stopped working. I didn't change anything from the script, and all the line does is check if v is a frame. I have no idea what's causing this. Here's the script (Btw its a local script):

local filterd = game.ReplicatedStorage.Filter
local fil = game.ReplicatedStorage.FilterBack
local check = game.ReplicatedStorage.Send2
local server = game.ReplicatedStorage.ServerCreate
local counter = 0
local precheck = false
local id
local id2
local check = game.StarterGui.Main.Scroll:GetChildren()
local fail = game.ReplicatedStorage.Fail
local success = game.ReplicatedStorage.Success
local player = game.Players.LocalPlayer
local newgui = player:WaitForChild("PlayerGui"):WaitForChild("Request").TextBox
local debounce = false
check.OnClientEvent:Connect(function(button)
counter = counter + 1
    if counter == 1 then
    id = button.Parent.ID.Value
    else    
    id2 = button.Parent.ID.Value
        counter = 0
        for i, v in pairs(game.StarterGui.Main.Scroll:GetChildren()) do
            if v:IsA("Frame") then --this isnt the problem line, its farther down
                if v.ID.Value == id + id2 then
                if player.PlayerGui.Main.Scroll:FindFirstChild(v.Name) then
                        v:Destroy()
                    end 
                    debounce = true 
                    local guiclone = v:Clone()
                    guiclone.Parent = player.PlayerGui.Main.Scroll
                    success:Play()

                    end
                end 
            if not debounce then    
            debounce = true         
                if v:IsA("Frame") then --problem line
                    if v.ID.Value ~= id + id2 then
                if #game.StarterGui.Main.Scroll:GetChildren() - 1 <= #player.PlayerGui.Main.Scroll:GetChildren() - 1 then           
                fail:Play()
                newgui.Visible = true
                    newgui.Parent.TextButton.Visible = true

                newgui.Parent.TextButton.MouseButton1Click:Connect(function()
                    filterd:FireServer(newgui.Text)
                    fil.OnClientEvent:Connect(function(filtered)
                    newgui:ReleaseFocus()   
                    local createserverelement = server:InvokeServer(filtered, id, id2)  
                    if createserverelement == true then

                    newgui.Text = ""
                        newgui.Visible = false
                            newgui.Parent.TextButton.Visible = false
                                success:Play()
                                        wait()
                                            debounce = false
                                        else
                                            if player.PlayerGui.Main.Scroll:FindFirstChild((tostring(filtered))) then
                                                newgui.Visible = false
                                                newgui.Parent.TextButton.Visible = false
                                                fail:Play()
                                        end
                                    end
                                end)
                            end)
                        end
                    end
                end
            end
        end
    end
end)

So if you could help, I would appreciate it!